Has anyone replaced the Stock Cats /w Aftermarket Cats and kept the Stock Exhaust can?

It would seem that most of the gains would be from using free flowing cats, and from what I've seen, there are some really cheap cat options!

- KJ

 

The cats are welded on. I suppose it could be done.

 

why? most the restriction is in the muffler system then in the cats themselves.

awe tuning only found 3 HP by running no cats....

 

OK, Thanks!

- KJ

 

I believe their test showed a 3 hp difference between the 100 cell and 300 cell high flow cats. This was why they chose the 300 cell cats for their exhaust system (high flow yet still able to pass the strictest smog tests).

I'd be willing to bet that going from stock cats to straight pipes would yield at least 10whp given the same rear muffler restriction. Obviously cutting and welding the stock turbo-back system would be required to swap just the cats out though - which may be a bit silly with the restrictive rear muffler still in the system.

 

It is not so simple.....see the exhaust mod thread. I had people send me notes swearing it could not work (the TJW mod) ever, and told me theories why. Well meaning all. People that added the adjustable valve told me they lost power....we gained it ......so it is not as simple as "if you do this, that will happen...." in all cases. It is subtle and experimentation is important.


Corollary: respect your tuner!

I know cats are out there. If someone does this, the keys are:

1. Figuring out where we get the cat...size/costs/shape
2. Does the mod make CEL's
3. Dyno data
4. Guess on cost (time) to do it, tools to do it
5. Video(s)

A 200 or 100 cell cat "might" give another 10hp or, better, let the peak go up.....


I think this is the next step in the cheap exhaust mod saga....



JB

 

I have stock 996 mufflers with race headers and cat-bypass (fabspeed).

With all my other stuff this car rocks. Revs like a motorcycle.

In my old 944T I took off the cat too and the turbo seemed to spool up faster.