Decided to purchase an exhaust

[RandallNeighbour]

I just saw a set of Turbowerx headers and they're very nice looking. You should check into those as well.

I have Che's headers on a non-egas 2.5 and love them. The HP gain is easily felt by the butt dyno.

[Cloudsurfer]

I currently have stock headers and FabSpeed's system on my S. It sounds great and I have a feeling it does flow better than stock. However, it does resonate between 2 and 3k which drives me nuts.

I have been considering TurboWerx's headers as they are beautifully made, B&B makes a nice set as well. If you want catted headers the only option are FabSpeed but they are $$$.

The issue with the CEL confusion and the 4 O2 bungs is this: the OBDII section of the DME expects to see different O2 levels pre and post cat to ensure catalytic efficiency, so having 4 O2 bungs in a non catted header is sure to get you a CEL. What you can do, is keep the factory secondary cats, or get high flow catted midpipes, and install a bung AFTER those cats and extend the wiring for the post O2 sensors. There will be a slight difference in resistance due to the added wiring but it SHOULD be ok.

I believe there are also some software reflashes that remove the catalytic efficiency monitoring, but I am not sure.

I would like to get the FabSpeed headers but I am simply not paying $2500 for them. My current plan is to get either the B&B or TurboWerx headers, and have my local custom shop remove the resonators from my FabSpeed midpipes and weld in high flow cats, and install my secondary O2s after those with extended wiring.

I'll keep you all posted if/ when I get around to this.

Patrick

Originally Posted by RandallNeighbour

I just saw a set of Turbowerx headers and they're very nice looking. You should check into those as well.

I have Che's headers on a non-egas 2.5 and love them. The HP gain is easily felt by the butt dyno.

hows the quality? any cels, and how was installation

[edevlin]

"The issue with the CEL confusion and the 4 O2 bungs is this: the OBDII section of the DME expects to see different O2 levels pre and post cat to ensure catalytic efficiency, so having 4 O2 bungs in a non catted header is sure to get you a CEL. What you can do, is keep the factory secondary cats, or get high flow catted midpipes, and install a bung AFTER those cats and extend the wiring for the post O2 sensors. There will be a slight difference in resistance due to the added wiring but it SHOULD be ok. "

I know different folks have had good luck with extending the wires to the oxygen sensors and locating them after the downstream cats without getting CEL-issues. But in my experience this can still give CEL's. I have spent the last 6 months on and off messing around with trying to get rid of the CEL. Car is running great but when I added the German TTP headers and 100-cell cats, I started getting the CEL.

In an attempt to resolve the issue, we tried replacing cats, moving sensor bungs, moving sensors into and out of the exhaust stream, replacing sensors, we even stuck in an new "used" ECU, it has been quite fussy.

"I believe there are also some software reflashes that remove the catalytic efficiency monitoring, but I am not sure. "

As I understand it, shops that do that mod can get in big trouble, at least that is what the folks that wrote the software for the chip in my car said.

In my car the CEL would come on after 70 miles or so of driving. To try to get at the cause of the problem, I left my car at the shop and the fellow that wrote the software for my chip would drive the car with the Porsche tester plugged in and wait for the CEL to trigger and then note all the values.

After several hundred miles of driving in this fashion, the "final" fix involved him reprogramming the ECU to have a modestly elevated threshold for the oxygen sensor level that triggers the CEL (as opposed to removing the cat efficiency monitoring).

As part of his trouble-shooting the problem, he ended up really tweeking and dialing in the chip for my car, the butt-dyno result so far is that the car runs and sounds better than ever, I cannt wait to get on a dyno to see what this latest ECU tune did.

So, this is one guys experience that messing around with the stock cat efficiency or extending oxygen sensor wires can result in CEL issues. This has been an expensive education.... have fun,


Ed

[Cloudsurfer]

Ed-

What have you been using for ECU modification? Very interested to hear more on this!

Patrick

edevlin,


This is probably way out there, but maybe it is possible that extending the length of the O2 sensor goofed up the latency of the readings and threw the CEL. What would rule this out is extending the length of all sensors by the same amount. That way they're all timed consistently. On the short ones, just tuck the extra wire in neat coil...

[edevlin]

"What have you been using for ECU modification? Very interested to hear more on this!"

The floks at Autothority Pitstop had written an ECU program for the 2.7 liter 217hp boxster. The program was customized for for a car that had a high-flow intake, headers and high flow cats. I had a chance to drive a 2000 2.7 that the mods and ECU tune and it was very fast, it seemed more responsive than 3.2 Boxsters I had driven.

So I decided to take the plunge and got the intake and exhaust mods along with the ECU tune. But whereas the other 2000 2.7 Boxsters with the tune never had a CEL triggered with the mods, mine did.

It may have been the cat efficiency on my 100-cell cats, the wiring when we extended the oxygen sensors, or even the location of the sensors along the exhaust stream, we are not sure. The folks at Autothority stood behind their work and put in a lot of time and parts to make it right.

In the process of getting my CEL to stay off, they really dialed in the chip tune for the stock 2000 217 hp boxster. As a result, my car is running better than ever. If all goes as planned, next monday I will get on the dyno I have used three times before to check on the state of the chip and exhaust mods to see what it says.

Ed

[admlmm]

Sorry if this does not exactly fit this thread but here is my recent experience with headers. I have a stock 2002 S (in Australia) and I replaced the OEM headers. These do not have the inbuilt 1st set of CAT's like the US ones seem to have judging by the other threads on the subject. The OEM headers have 34mm external diameter pipes with 40mm (approx) internal diameter (ID) collectors. I installed a set of aftermarket T304 headers (Porsche Tuning) that look like those attached . They have 45mm ID pipes with 50mm ID collectors. I chose these because they had 45mm ID pipes whereas it looked like the Maxspeed ones, whilst looking the same, had only 38mm pipes. Their collectors were the same 50mm as the others. The Porsche guy commented to me that the after market headers looked very well made but showed me that the Gambella ones were better due to smoother internals from the welds. He commented he too would not have spent the extra money on the Gembella's as mine seemed pretty good. You can see in the OEM shot how poorly the OEM pipes merge into the collectors compared to the aftermarket ones. I videoed both before and after and ran the recording through a sound measurement program my son found on the net. Sorry the forum tool will not accept the videos. We measured the camera distance to the exhaust pipes to keep the same. We tried to keep the revs the same but this is difficult to achieve for a couple of hacks messing around in the garage. The results are by no means scientific but indicated to me that the car is actually slightly quieter now than with the original headers. This is supported by my "impression" of driving it. In fact it is now so quiet I cannot believe it is the same car. The car appears to spin out through the revs a lot quicker and seems to have more punch. I have a fairly serious corkscrew ramp at the office and used to just let it idle down with the engine braking keeping my speed in check. I now have to dab the brakes as it seems like a lot of back pressure from the engine has been relieved. I did want a more sporty sound and if I got more power that would be a bonus. I am pretty sure I achieved the latter but not the former. I guess I will have to fit a cat back exhaust now to get that sound. I was frightened off installing the headers myself by all the talk of broken studs and got the local Porsche shop to do it. As luck would have it no broken studs and probably about an hour for the total job. The car only has 44 thousand kms (27 thousand mls) and has never seen serious rain or cold weather so maybe that is why the studs were not frozen. No CEL's which is as I expected as I have not messed with the O2 sensors. Now, why would larger diameter pipes and collectors and better designed merges translate to lower engine back pressure and less noise? My guess is more laminar flow of the exhaust gasses than the turbulent flow created by the terrible OEM headers. That translates to less pressure loss from the headers and an increase in efficiency. Some other observations I have that may help others. The Fabspeed system looks very well made but I will agree is relatively expensive to other after market systems. From their video it seems they claim an advantage over the others by having 2" inlets into their muffler compared to 1 and 3/4 of the others. As much as I am attracted to that I can now not easily fit their system as the bulge in the intermediate pipe is a resonator and not a CAT so I would then have no CAT which would not be good. Their system has the CAT incorporated in their header so you really have to fit their entire system to make it work easily. It seems as though they have also altered the rear connection position between the intermediate pipe and the muffler so I cannot easily just fit just their muffler. I will probably end up buying Che's muffler as it will bolt straight onto my OEM intermediate pipe (containing my CAT). The only choke I will then have is the smaller diameter OEM intermediate pipe and CAT which may be another project for the future. In hindsight I probably should have just gone for the full Fabspeed system in the first place.....