Catalytic converter sizes: is bigger better?

[freakie]

I dont think its the case that its 1.3% all the time, though Im not sure I believe its exponential?

[mugsee]

Thanks for the link to that 'ballistics' cat - it seems to kick ass, even over metal cat. Is this what you're running at the moment?

One thing that I've learnt through asking this question is not to compare cat converters by their opening and closing diameters (as we do with exhausts), but rather to take into consideration the diameter of their catalytic conversion chamber and also the length of this chamber. Both these properties play a (what looks like) bigger part in the flow of a cat converter.

My original question asked was very vauge and I apologise for that confusion that its caused.

I gained 5 kws from changing my 3 inch to a 4 inch cat, my car made 374kws at the wheels before the 4 inch cat and after, it went to 379kws.

I guess its only better if its actually a restriction in the first place.

Is the 3-4" reference to the length of the cat or the diameter of the cat chamber, or the inlet/outlet diameter? If inlet/outlet, did anything else change? Thanks

[tinkerbell]

Thanks for the link to that 'ballistics' cat - it seems to kick ass, even over metal cat.

yes, seems to!

Is this what you're running at the moment?

i wish.

the 2.5in "high-flow" ceramic cat i am running now is certainly a possible restriction...

[kavehman]

Has anyone tried the e bay ballistic cats. I have seen a few on Ebay USa for around 100USD Shipped.

I wonder if there any good.

[funkii]

maybe it will bigger whole more air = high flow ? not much gain but ? ?

[freakie]

the internal diameters were changed, the cats used are all straight through, the size of the pipe doesnt change, well not the ones i have got