968to986

Broadfoot Racing also sells systems for our cars, though I don’t know how the quality rates.

Nowanker

I can recommend Fabspeed.
I've installed their stuff on a bunch of different models. 911, Boxster, 951.
Always had good fit and quality.
First choice for my own car... Not affiliated.

MM951

Granted its been years, but I didn't notice anything worth spending the money on my 951 with an old 60-1 hifi when I went from a 2.5" test pipe to a 3" stainless exhaust. Stock downpipe. The 2.5" straight pipe also sounded 1000x better than the 3". I would have kept it but the Bursch test pipes (back then at least) weren't stainless and eventually rusted out.

blade7

I'm fairly confident that nicely polishing an exhaust systems adds zero bhp. And an after market exhaust system on it's own, probably adds less than 10 bhp.

GarageYears

First, I always find the names used for the various pipes confusing, so let me get those defined first...
- The pipe directly from the turbo I call the "turbo outlet"
- The following pipe is most often called the "down pipe" and the factory one includes the catalytic converter (for both the main outlet and the wastegate)
- The final pipe I call the "muffler pipe"

On my car, so far, I have replaced the down pipe with the Fabspeed 3" cat delete pipe (I think they call this the "down pipe+test pipe", so the cat is gone. I also have the Fabspeed 2.75" turbo outlet pipe, but currently I haven't fitted it, as I am waiting until I need to pull the turbo.

On the Fabspeed site they claim +26WHP and +29ft/lbs with the 3" pipe replacement. Now I think that is if you do BOTH downpipe and muffler pipe, but it's not clear.

What I CAN say with the down pipe cat delete, I noticed a positive gain in turbo spool up (reduction in lag) and definitely some power gain. Can I put a number on it? Well, I haven't had the car on a dyno, but combined with the LR Max chipset and the other stuff I've done, I know the car is quicker now.

I also like the change in sound - I can hear the turbo spool up and have a little more growl. Nothing crazy, but it works for me. Currently, I'm debating with myself whether to do the rear muffler pipe - if I do, it would be the Fabspeed 3" Maxflo. That pipe alone is $1300, so non-trivial, but I will mostly likely do it later this year.

blade7

Didn't Porsche state that the power output was the same, regardless of whether the cat was fitted on the 944 turbo? And AFAIK the Lindsey and Fabspeed discharge pipes neck down to 2.75" dia at the turbo.

GarageYears

Well... here's someone that actually tested things:

"There are multiple parts to the 944 turbo exhaust (in order of flow): Headers, Crossover pipe, turbo outlet, Test/Cat pipe, Catback with muffler. I will eventually try and hit them all, but starting with the basics.
Best bang for your buck out of a 944 turbo, is to get rid of the catalytic converter. Some states emissions will prevent this, but if you can pitch it, get it out of there. Getting rid of the cat will free up about 20hp on a stock 2.5" exhaust. It can be replaced cheaply with a bursch test pipe for $300, or you can upgrade to a 3" full exhaust (test pipe and catback) for more money. Like I said though, most of the hp gain will be the deletion of the cat. My dyno tests have shown that a 3" exhaust over a 2.5" catless exhaust shows gains of about 4hp and 7tq, making the total gains around 25hp over stock. If your exhaust system is starting to fall apart, then my all means, go with the 3" full system, get the maximum power, and a little less weight. The stock muffler is a straight through design, so any changes to the muffler alone, will only result in change in tone, and not gains in hp. If you must pass emmisions, then there is always the option of going with a 3" exhaust and a high flow cat."

That's what I felt with my car when I deleted the cat and went with the 3" down/test pipe. This comment is also why I'm not in a rush to replace the muffler section...