Fabspeed Bypass Pipe-Any Experiences Welcomed.
 

Hi Guys,
I have a 2002 Boxster S and I thinking of installing a Fabspeed secondary cat bypass pipe. These pipes eliminate the secondary cats. I would like to just use the Fabspeed Bypass Pipes and still use the stock 986 2002 Boxster S stock muffler.
I wondered about the new exhaust sound, if any, and how it may compare to the stock sound with the secondary cats.
Also, do you think there would be any noticeable increase in HP.
All comments will be very much appreciated.

This topic has been commented upon ad infinitum. In any case, there's no real horsepower to be gained by simply eliminating the secondary cats . However, it will reduce a fair amount of unnecessary back pressure, and give your vehicle a slightly more aggressive sound. Perhaps, most importantly, it will shed a significant amount of weight . And that in and of itself can have it's performance advantages .

seeing as johnny you are the exhaust guy as it were, how do u feel about a full cat-less setup with a stock muffler? (sorry I dont mean to hijack.)

I just did this mod a few weeks ago, only the pipes, everything else stock. Sound is deeper, not huge difference, but better. Thebcar feels like it breathes better, revs quicker, so may seem like more hp, bu not sure. One of my cats were startingnto deteriorate, so the my hve been partially clogged, but either way, now, the car seems to run better and rev quicker.

Based on my experience, you'll lose a significant amount of low end and mid range torque.
Not to mention CEL's galore . In addition, the oem muffler is extremely restrictive . Personally, unless your budget will allow you to purchase a set of high quality headers and cats, I would stick with the oem headers/pre-cats , delete the secondaries, and replace the oem muffler with a suitable aftermarket one . There are numerous brands across a wide price spectrum that will not only weigh considerably less, but will provide better exhaust flow and sound superior .

See my sig.

I am running completely catless and have not had issues, but retaining the stock muffler would not be good. I chose to purchase an oem Eisenman built PSE and the sound is really nice. That version will fit up to MY '02.

As far as aftermarket headers, I chose Turbowerx and they deliver results. You need to find a good indy mechanic and he will know how to keep your O2 sensors from triggering a CEL. It can be done.

I have had only one CEL after having my setup for a year. I purchased the Durametric cable, downloaded 6.0 software and it was gone in seconds..

To get good results, you need to take the plunge and do all exhaust replacement from the headers to the muffler. Just don't buy junk or you will not have a good experience...

All in all, I have 800 in headers, 500 for the Fabspeed pipes, and I think around 13-1400 in the PSE. Bought it new off Ebay a long time ago. They sometimes surface...If not, they can be had close to 3k now, but other manufacturer's like Fabspeed make a good muffler.

I have not run my car on a dyno, but can tell you that additional power is being made. Sound is very nice too.

With all due respect, the additional power that you are experiencing must be in the upper rpm range . Clearly, your system is more characteristic of how track applications are set-up, wherein the concentration is much more focussed on high end power. Virtually every boxster that I know (most importantly my own), lost low end to mid range torque when run completely catless . Furthermore, with that set-up the only way that I'm aware that one can truly rule out CEL's is to re-map the ECU. And, that comes with it's own separate cost .

Luckily I have a ROW tune on my car. My only issue that I have is purely sound. I have a deluboz v1 muffler which is nice and light but with the cat-less setup (ebay headers [which by the way seem to be built fairly well and are wrapped.]) and my own made bypass the whole thing is just too raspy and well I think too low on the back pressure. I was hoping adding an S muffler I might increase some of the back pressure and possibly gain some of the lost low end power... but idk if it works like that. I also put on a very small UDP from precision chassis works for good measure.

One day I would like to put the car on a dyno and see what kind of numbers come about.

And yes Danger, the only "fool-proof" way of doing away with the CEL is to reflash with one of the many flavors of aftermarket or RoW software out there.

Wicky Lawrie - 615-226-4928, Owner of Renntag Motorsports, Nashville, Tn [I]was able to defeat the CEL for nearly a year with the install of the headers...

I was shocked too when he said he could do it, especially after reading these forums for so long, but this guys ROCKS!

Anyone near Music City USA needing Porsche service needs to call this man! He knows his craft and is not expensive. You may have to leave it with him a week or two, but it is worth it! And cash is king...

I'm new to the forum and this my first post. I am considering doing the exact exhaust mod you just described on my 2003 986. I'm looking at the Fabspeed Maxflow exhaust system with the 2ndary cat delete pipes and a performance muffler. I'm also researching the FVD Brombacher "Sound Version" muffler with the secondary cat delete pipes. However, after reading some of the posts on other threads about in-cabin drone and resonance, I'd like to be able to meet another member who has already done either mod and hear their car in person. I live in Laguna Niguel, CA (Orange County). If anyone with the mods lives in Southern Cal I'd love to meet them and check out their mods. Please send me a PM. Thanks.

There are youtube videos of the Fabspeed Exhaust sounds from inside the car and outside. You can access them from Fabspeed.com when looking at the products, or you can go to youtube.com and manually search them.

the effect of the bypass pipes on sound largely depends on your muffler. with a reasonable muffler, the sound is deeper & more throaty. in my car, which has a race muffler and no sound deadening, the exhaust is MUCH louder with the bypass pipes; more like a cup car.

that having been said, i have an extra set of brand new T304 stainless bypass pipes i'd be willing to part with. caveat: they are designed to work with mufflers that have a larger 2" inlet rather than 1.75" like OEM. i will post a pic later.

PM me if you want them; they could be necked down like the fabspeed pipes pretty easily. $300 for the pair.

do the ebay headers and leave the stock mid-pipes/cats. that's how porsche does it in countries with less strict emmissions requirements.

north america has the added requirement for emmissions reduction at start-up, so american cars have an additional warming 'pre-cat' on the headers and a secondary air pump, as well as sensors and ecu programming that checks to make sure both are working. row does not have this requirement, so row cars do not have cats on the headers or secondary air pumps, and no sensors to confirm their operation.

you can get catless, equal length, stainless headers on ebay for $65; the cheapest you can get new catless midpipes is $500. get headers without cats, however, and you have to deal with the sensor that is there to confirm the operation of the now-absent cats (or you get a 'check engine light'). you can reporgram your ecu to row, you can buy 'foolers' (fvd sells them) or you can make your own. all the sensor does is look for 02 content in the exhaust. it can be fooled into thinking that the cat is working by distancing it from the exhaust; some guys just hang it under the car, or you can get spark plug savers that thread into the exhaust bung and get the sensor out of direct exhaust flow (make sure your new, catless headers have two bungs each). there is also supposed to be a trick that uses a resistor or diode wired into the sensor; google is your ally for cheap, easy solutions to this.

other considerations are pipe diameter; oem for a 3.2 is 1.25" into 1.75" (ebay headers vary, but 1.5" into 2" is typical); go much bigger than this (or go completely catless or to a high-flow muffler) and you get into backpressure issues. reduced back pressure is good at high rpm when the engine is trying to flow as much air as possible, but at low to mid-range some back pressure is necessary to facilitate combustion chamber scouring and make max power. i've yet to see a dyno of just a high flow exhaust that does not indicate a drop in hp/torque at lower rpms. that's why most dynos from tuners include ecu flashes to compensate or don't start until 3000 rpm to hide this fact.

other things i've read is that cats tend to kill high frequencies, so a catless exhaust can be ricey sounding. also, i've read that those who have compared row to us spec cars have found the row to only be several hp stronger, so better figger out what your $/hp threshold is. i can justify $65 for several hp; uncertain if i can justify $500 for the same gain.

ps - lobo; what's the word on the wrap - worth it? keeping things cooler at all?

With all due respect, at 600 cells the secondary cats are arguable the most restrictive (and possible the heaviest) part of the oem system . Therefore, if one is going to leave most of the system intact, it would be far better to leave the headers/pre-cats in place and remove and bypass the secondaries .

True. Plus, no cel with properly built pipes. The secondary cat pipes weigh close to 30 lbs. The bypass pipes? 8 lbs.

Total weight savings on my full exhaust was about 80 lbs.

weight aside, the argument becomes where the remaining cats are located for best performance - on the headers or on the mid-pipes. porsche and cost say delete the cat on the headers.

changing mid-pipes is easier; no potential seized bolts in the block, no sensors to deal with. however, here are some links to three easy ways to fix the cel issue:

http://forums.evolutionm.net/evo-how-requests-questions-tips/215795-5-o2-cheater-non-fouler-how.html

http://www.fvd.de/us/en/Porsche-0/-/-/-/item/item_details/VID_33179399-VCD_85527367-gid_29-sort_4-display_50-item_FVD111LAMVER/EXHAUST_-_Tuning_-_Catalytics-FVD111LAMVER-Oxygen_Sensor_Extension.html

http://www.audiworld.com/tech/eng53.shtml

otherwise, everything i find on the intraweb says that the pre-cats are more restrictive than the main cats ...

Ideally, if one could eliminate the oem header/pre-cat design in favor of a set of high quality aftermarket headers that incorporated both larger diameter and longer equal length primaries that flowed into a well designed merge collector, along with a pair of high flow cats (something on the order of 200 cell tri-metal HJS or Emitec cats) that were located mid stream - that would prove to be a very effective system indeed. However, in order to accomplish something along these lines, one would have to spend big buck$$ ! Especially, with the cats . Having said that, unless a person's budget would allow for this kind of expenditure, the best option would be to remove and bypass the secondary cats. The 986 boxster shares the same secondaries as 996 platform vehicles. And, at 600 cells, these cats are much more restrictive (and heavier) than the pre-cats which are 400 cell .

the ebay headers are copies of expensive headers (slightly larger diameter, equal length primaries, etc.) so the the differences between $65 and $1000 headers become very small (ie, porting, polishing - most things you can fix with a dremmel) and any power improvements negligible.

regarding the cats, please show my anything that confirms that the cats on the mid pipes are more restrictive than the cats on the headers. here's a previous post by a board member regarding cell count:


Quote:


"Anybody have any idea how many "cells" are in the OEM primary and secondary cats?

I've come across differing information. In the past, I've been told that the primary cats are 400 cell and the secondaries are 600. However, I tend to think that they're 400 cell all around."

so, either the cats are the same, or the cats on the midpipe (the 600 cell secondaries) are more restrictive. either way, best money and performance are on the ebay headers and leave the midpipes as-is.

Throughout my entire experience conducting exhaust mods, I've both read and have been told by virtually every knowledgeable exhaust "tech" and "tuner" that the secondary cats on the 986 were 600 cell .

There is a lot more to it than that......

yup, and a lot of that has to do with tuning the exhaust to maximise exhaust gas scouring at lower rpm, improving low rpm flow efficiency while maintaining backpressure, etc., all of which supports locating the cats further downstream and improving the headers.

ps, the quote about both cats being 400 cell was made by JD in a thread from about a year ago, so caveat emptor to all.

http://986forum.com/forums/performance-technical-chat/25644-pre-cat-bypass-vs-secondary-cat-bypass.html?highlight=600+400+cats

Since that thread, further research and discussion on the topic lead me to discover that the secondary cats were 600 cell . I've always been someone who strives to enhance his knowledge about things. Particularly, when there seems to be a lack of reliable information . And, by doing so, I am able to better understand what it is that I am dealing with (in this case my vehicle), and hopefully be able to pass on what I have leaned to others .

I've got the Top Speed Pro-1 test pipes and they improve the sound at idle, making it a bit deeper. The car also sounds better as you rev it, but I don't have any recordings.

As to power increase, it's been so hot that I can't fairly judge but maybe some due to the improved flow and saving 7 pounds per side.
When the weather gets cooler in October I should notice a difference.

A worthwhile mod based on my experience.

I'll post before & after vids this weekend.

I found a very helpful link to an explanation that helps understand the difference between the OEM 986 exhaust and a modified performance exhaust system (in this care, the Fabspeed Maxflo system):

http://www.fabspeed.com/videos/Boxster%20986%20Maxflo%20Muffler%20Explanation%20V ideo.wmv

This may be pretty basic for those of you who have a lot of experience with these mods, but it really helped me understand the differences between the OEM system and a performance system. Thought I'd share the link for anyone who is researching an exhaust mod for the first time.

Thanks, M96!

shot some video w/ OEM cat pipes vs. fabspeed bypass pipes. will post today.

some clips comparing OEM vs. bypass.

engine is a 3.4L with a custom intake, headers & a stebro race muffler. the OEM cat pipes are from the 2.5L. the bypass pipes are 2" fabspeed.

http://vimeo.com/28638915

After posting that video, I got a call from these guys .

never exceeded 5 over..... :rolleyes:

Does current information suggest that installing secondary cat delete pipes and a Pedro style/pse style bypass exhaust muffler (modified stock s) will reduce back pressure (and therefore alter exhaust scavenging) to such a degree that there are losses in torque and power? Can one simply look at what the computer has done to ignition timing to see if it has detuned the engine via ignition retardation, to get an idea whether an exhaust system is working well? What are the stock ignition parameters and what variance would be bad as seen via the OBD port?

Yes I know dynos are the tool I am dancing around!

you have to consider the whole system and the REASON backpressure is a concern (it's not).

most people talk about backpressure like it provides something to the equation. well, again, we have to consider the SYSTEM. scavenging depends upon VELOCITY in the exhaust gas. the velocity is what creates vacuum at the valve outlet. if the pipes get too big early in the system, velocity stalls and pressure increases. this means no scavenging. we also have to consider that as the exhaust gasses cool, they condense a bit, leading to further loss of velocity (this is why people try to keep the heat in headers).

ideally, you'll have a properly designed header. the length & diameter of the primaries will be tuned to the engine's parameters (valve timing, duration, diameter, angle) and to the desired performance charictaristics of the user (high-band power, low-band torque). they will join into a merge collector that is a venturi. it will neck down slightly & then open up a bit (like a megaphone). the header itself will accelerate the air past the venturi (secondary flange). once this happens, you want LARGE pipes; back pressure is not a concern.

if you're using non-venturi style headers or the OEM manifold, it's not the loss of cats & backpressure that causes the problem. it's velocity loss due to the DIAMETER of the tube. the bypass pipes are all 2", but the OEM pipes are SMALL. this means that you'll lose velocity & scavenging lower in the RPM range. there may be some improvement at the high end. all else equal, removing the cats will greatly improve velocity & in turn, scavenging.

with OEM exhaust manifolds, 2" bypass pipes and the pedro muffler, you will probably lose power overall w/ the 2.5L and 2.7L motors. there MAY be some high end power gains. the 3.2L and 3.4L would probably make power.

if you go w/ decent headers on the 2.5L / 2.7L, the bypass pipes & pedro muffler will make power up high, but lose some torque. i found the 2.5L to be gutless w/ torque anyway, so i always opted for high RPM power & revved the crap out of it. much more fun for me!

Don't worry .... I told them to give you a break away ! :)

i was SUPPOSED to be at the track today, but tropical storm Lee had other plans. date has been revised to 9/15.

i will take some video so you all can get an idea of exactly what a well tuned, stripped out boxster w/ a 3.4L can do when i REALLY get into the go pedal....

Hey insite, are you still using the wheels shown in your sig? With as performance-minded as you are, I'm surprised you don't have something like an Alleggerita.

believe it or not, the BBS forged 2-piece are already fairly light. at some point, i will probably go lighter, but i have a lot of other things to do first....

Thanks for your thoughts......yes of course scavenge velocity is king! Can't wait to see the video. I have just had my butt kicked by 996 4/996 T

I have the same wheels from Porsche but they were three piece...BBS is actually the manufacturer. In my view it will be tough to find anything much better in 18"

My wheels are the Porsche version (sport classic II). I will try to deliver some payback to the 996 TT's; 1 or 2 going w/ us next week.....I think they will find it hard to keep up. :D

if anyone is interested, i have some photos showing the differences between OEM, fabspeed & deluboz pipes here:

http://986forum.com/forums/boxster-cayman-parts-sale-wanted/30237-cat-bypass-test-pipes.html

the deluboz prototypes (brand new) are for sale. gorgeous parts.

I installed cat delete pipes with an all stock exhaust system. My secondaries we starting to break down, but i definitely do not feel a power loss. I believe they are downstam enough where back pressure is more trivial