I was wondering for those who have run Fab Speed cat by pass pipes, did you get a CEL light??

Thanks,

 

I do get it. Car runs fine though.

Other people don't get it.

I have tested my car with FabSpeed Sport mufflers (sold), muffler bypass pipes (sold) and 996 PSE (loaner). I liked the stock sound better. With the cat bypass pipes, few people notice the sound difference. I like it better than the stock sound.

The killer setup in my opinion is the FabSpeed headers with the Eisenmann Ti exhaust (cats and mufflers) with a weight of only 30 lbs. Get custom made straight pipes from the headers and you can easily swap the exhaust system in 20 minutes.

 

don't get it
like it - sounds good and runs a little less weight

 

btw, I didn't notice any increase in power with the cat bypass pipes. I did notice the increase with the Fabspeed mufffler and the muffler bypass pipes.

 

Any power gains with the headers?

 

I was struck by how reasonably quiet all the GT3 Cups were at Laguna last weekend. When the World Challenge GT3 RSR's went by the ground shook, but the stock Cup headers and exhaust are much more quiet. Of course the system costs $5k or so.....

 

JR

I wonder why Porsche uses a muffler on the Cup car, while the RSR uses straight pipes from the headers.

Some GT3 street cars are using muffler bypass pipes.

I might try my car on the $15 PepBoys muffler bypass pipes combined with the cat bypass pipes, to see if there are any noticeable gains.

 

I think because Porsche wanted to make the GT3 Cup more of a street variation track car. Also of note, the muffler has an intregral catylic converter.
On the other hand, maybe it was just to conform to sound requirements (like 103db) at certain tracks....

 

I have the FVD bypass pipe which you can mount your stock exhaust tips on, unlike the Fabspeed setup.
I have had them on my GT2, I love the sound. Yes the CEL comes on but only in city driving/stop and go traffic. Hard to avoid those circumstances in Chicagoland.
CEL code is set for "Cat. Efficency threshold".
Car always runs fine, I have taken them off recently but will put them back on after chip tuning is done to thwart the CEL. Once you have them on you will not want anything else . I have the Fabspeed sport exhaust and after the pipes that is tooo sedate for me. Nothing like hearing the TT's spool up.

BBGT2

 

I just dyno'd my Mark I GT3 Clubsport with the Fabspeed parts in various dyno runs to see what the real story is at the rear wheels.

If you go Fabspeed GT3 headers + cat bypass + muffler bypass, you gain 8hp at the rear wheels. Put the stock GT3 headers back on the car and you gain 12hp. The car wants some limited amount of backpressure to maximize power. So you either run the slightly more constricted factory headers and bypass the cats/mufflers (but its loud as hell -- appropriate for track use only); or you go for the Fabspeed headers with their big merge collectors but need to run a 100-200 cell race cat or sports muffler to create a bit of pressure in the system. Opening both up actually creates less horsepower. I'm going to likely dyno the GT3 Cup race cats with the Fabspeed headers as my next test to see what happens. By the way, I run the BMC replacement filter for the stock airbox. Fabspeed has a variation of the PMNA Cup (carbon fiber) airbox with cone filter for $795 but no dyno results to qualify whether it produces any real hp/torque gains. PNMA knows that the carbon fiber airbox on the Cup cars is good for 10+ hp.

Since my car is a track car, I could care less about a warning light but I haven't had one (yet).

 

FabSpeed has some dyno figures on their web site. The combination producing the most power was the cat bypass pipes/sport mufflers. The muffler bypass pipes didn't increase power that much, but a 45lbs weight reduction is convenient.

Finding that the improved headers lose power vs. the stock ones while no cats/mufflers is really interesting.

I'm not sure if the FabSpeed headers with sport cats and muffler bypass pipes can help that much. The more restrictive stock cats with the restrictive stock headers and no mufflers didn't produce great results on the FabSpeed dyno testing.

I would try the FabSpeed headers, no cats and the FabSpeed sport mufflers. This combination reduces close to 40 lbs and you will have more back pressure than sport cats/no mufflers, but obviously it needs to be tested on a dyno.

My car feels stronger with no cats and stock mufflers than with stock cats and FabSpeed mufflers (nothing tested on a dyno, just my perception). When I ran stock cats and muffler bypass pipes, the car was loud but it didn't feel as strong as when equipped with the Fabspeed mufflers.

 

No cel light yet and I've done 8 track days(with bypasses) so far. I use just cat bypass with stock mufflers. You'll save about 20 lbs overall with cat delete. Only issue which not an issue for me is at lower rpms as it drops down can hear mufflers resonate a bit but at the track no problem. I don't notice ne loss of power but maybe little better midrange but who knows sounds good after 4500 rpm to redline. Mike

 

I talked with Joe Fabiani at Fabspeed and I think we've concluded that the reason my Mark I GT3 reacted better with the stock headers is that I did not tune the car (ECU) for the new header set-up and the Mark I GT3 has more aggressive cams than the Mark II cars. I think with the 2004+ (Mark II) GT3s there are indeed some gains by usuing the bigger headers/merge collectors. The Cat Bypass is DEFINITELY an area where horsepower is produced -- but the biggest part of the gains are in the upper range (over 5,000 RPM) so that's perhaps why guys are not noticing it under 60mph. The problem of running them on the street is state inspections where "emissions sniffers" are used -- so you need to switch them out to obtain inspection stickers each year.

 

on regular driving I didn't notice any power increase with the cat bypass pipes , but when I drove the car on 2 recent Solo2 events, I could feel a better response on the high rpm.

For weight reduction, a combination of cat bypass pipes and FabSpeed Sport mufflers is hard to beat (close to 40 lbs lighter than stock) for the price, and their product quality is much better than the stock Porsche product. This is something that can be driven on streets because is not sick loud.

The muffler bypass pipes are extremely loud, and they don't seem to produce more power. The weight reduction on them is 45 lbs and not 50 lbs (assuming stock cats), because the pipes are 2.5 lbs each. I hated them, I felt pain on my ears and headaches, that's why I sold them. Not for use on public roads unless you want to get pulled over every day.

The Ti exhaust from Eisenmann is 30 lbs, and it includes cats, mufflers and tips. That's is 44 lbs lighter than stock at a price of $5k retail. This is something that can be used on the streets as well.

Combining the cat bypass pipes and the muffler bypass pipes might reduce back pressure to the levels where the car is losing power, the car will be too loud, and the weight reduction is 59 lbs. It should be interesting to test it on a dyno. I guess this combination is as loud as the one day I started up my car with just the headers.