2004 Boxster S dyno w/Fabspeed Cat Bypass Pipes
 

I did with and without dyno runs with the Fabspeed 2nd cat bypass pipes. The car is a 2004 Boxster S Special Edition with 17k miles (de-snorkled). The baseline runs showed 228 whp. With the bypass pipes installed, the dyno showed 237 whp with a negligible/no change in hp curve. Given all the slight variations run to run, etc, I'd say the Fabspeed claim of 8 hp for using the pipes appears to be accurate, at least on my car.

I've seen posts for non-special edition cars on this forum dynoing at 230whp so I was a little disappointed with my car being shy of 230 whp on the baseline runs. However, given the variations dyno to dyno, ambient temp, etc it's certainly within reason.

As always YMMV.

Mike

I also have the Fabspeed secondary cat bypass pipes on my '02 S...whether or not there is a power increase, the sound the bypass pipes create is worth the price of admission.

"228 whp stock. With the bypass pipes installed, the dyno showed 237 whp"

Wow, 9 whp with just bypass pipes, that would be great, but it seems high to me. What were the conditions of the dyno runs?

Ed

:cheers:

Same day, same dyno, about 80 degrees +/- for the 1st set of runs with cats, about 84 degrees +/- for the 2nd set of runs with the cat bypass pipes a few hours later. The car may have had ever so slightly lower water and oil temps for the 2nd set of runs, but it would have been very slight as the car was street driven a little prior to the 2nd set of runs. Given dyno variations run to run (+/- 2-3whp), I'd say 6-9 whp is where they came out for me (2 runs each 227/228 and 234/237)....giving the 9 whp best run vs. best run and 6 whp best run vs. worst run.

Not earthshattering by any means, but I was glad to see the numbers come close to what was advertised by Fabspeed for me at least. Looking at the hunks of metal the bypass pipes replaced I would have been absolutely shocked to see anything less than 5-6 whp.

BTW - the car really hates the dyno. It won't dyno at all with PSM on and although it will with PSM off, you get all kinds of "drive immediately in for service" messages afterwards until you drive the car a bit on the street and let the systems reset.

As you mentioned, the other benefit of the bypass pipes is removing considerable weight off the car. I was surprised at how much those cat/pipes weighed when I pulled them off. The real treat is the mid range sound produced by the bypass pipes...comes in full song at around 3800 rpm.

awesome mike!!! did you dyno at SR racing? Ive got to get my car over to a dyno to get a baseline before we finish up my intake system on the 3.6

Yes, at SR. Please let me know what the 3.6 does on the dyno. Also, show them where to pick up the tach signal on yours for the dyno that way I won't have to next time. :) None of my runs had the torque line on the print-out.

my attitude is given what these parts cost - if you need a dyno to detect the difference in power - the power gain wasn't worth it. if you like the sound - great. but if you can't FEEL more power - then it's not that much.

can you FEEL the power gain by the seat of your pants butt dyno?

i've modded quite a few cars, and many of htemods I did, produced such small gains that I honestly couldn't feel it - or could only feel it at upper upper high rpms....

on my 2.7L - not sure what kind of gains I'd get by doing cat bypass.... less than 8hp... i'm sure. i would probably wait until the dealer tells me my cats are clogged and I need new ones, then get these and just get rid of them altogether..

I'm very happy for you. Just think how much money you'll save on modifications! :)

O2 sensors
 

MTS, is there a provision for O2 sensors on these pipes and if not how do you solve the fore & aft sensors on the pre cats? Sounds like you got as much seat of the pants gain by losing the 25 lbs along with the 8 hp. Any torqe gains as this is what we really are looking for?

AKL

There are no O2 sensors on the 2nd set of cats or the cat bypass pipes. Both pre & post readings come from the 1st set of cats attached to the headers. Therefore, there's no problem to "solve" no CEL's.

The dyno didn't track the torque line. However, it's just a math formula and I had speed and horsepower from the dyno so I just plugged in the tire diameter, differential gear ratio & tranny gear ratio and did a spreadsheet for the torque line. It shows a peak torque difference of 8 right at 4,000 rpm with the average area under the curve improvement being about 4-5.

As for the "seat of the pants" I'm not certain my butt dyno is sensitve enough to accurately determine an 8hp/8tq difference......that's +/- 3% which is why I took it to the dyno to start with. However, it does give you a little power benefit, increases the volume of the exhaust note a bit and saves some weight, all good things in my book.

There's precious little that can be done to these cars to increase the horsepower in a price-effective way. For me, the slight power increase combined with the slight sound increase (paired with my PSE is just lovely sounding BTW) was worth the price of admission. For some others I'm sure it wouldn't be.

:cheers:

Why don't you post some sound clips (in both PSE modes)? I have the PSE on my 04 S and have been considering the Fabspeed bypass for a little extra sound. I have already seen the youtube video with this setup, but I would always like to hear it again.

So correct me if Iam wrong all this is only installing mid pipes right?

The mid-pipes did add a little exhaust sound for me, primarily in the 3800 and up rpm's. However, I would not describe it as dramatic. My exhaust didn't really come to life until I added a PSE.

Forgot to mention I have a Pedro (PSE) Sport Exhaust on my car. It's fairly loud when you get into the throttle, but cruises nicely with no resonance.

With all this talk of "cat bypass pipes" I visited the www.fabspeed.com web site. $495 for a pair of pipes? Wouldn't it be more cost effective to have a local muffler shop fabricate a pair for my car? Any draw backs?

just picked up a brand-new pair of fabspeed bypass pipes for $230 (incl. shipping) on eBay :D

Chris,

One time good deal or do they have more? Was it from an individual or company?

It was from Suncoast. http://stores.ebay.com/****************************************************
I think it was an individual deal to get rid of some stuff on their shelves...

Anyone care to make a video with the fabspeed midpipe and stock exhaust?