Which cat do i need?

[djt]

Hey, Im in need of a cat for my exhaust system but im a little confused, i have rmf headers which are 2.5" outlet and a vision 2.25 cat back/b pipe. which cat do i get? A 2.5" or a 2.25"? Or do they make cats with one end 2.5" and the other 2.5"?? And also what brands and cell(100,200, highflow,etc) should i be looking for?

Thanks heaps

[ceekay101]

Meow. You should probably ask the exhaust shop, who will be putting it it. But my understand (which could be way off) is that less cells provides better flew, but gives it more pollution. Also to attempt to max flow possibly 2.5 inch cat then some sort of joining piece from 2.5 to 2.25.

[junoki]

^ +1

get the exhaust shop to weld on suitable flanges to the header side and the pipe side

[nate92]

200 cell will pass emission test but 100 cell is less restrictive but won't pass.

You can get any exhaust shop to fit it in, just weld a flexi pipe to suit ur need

[muzukashi]

You never said what car it is but you would probably be looking at a 2.5" cat with welded flange/flexi to suit the system - Mentioned above exhaust shop will take care of you here,
Get a xforce/magnaflow both reputable brands don't go for random ebay brands they tend to crumble which ends up making your car stink like shit

[djt]

Oh shit my bad, the cars a ek4 vtir. The reason why I ask is that I want to get the cat myself rather than buying it off the exhaust shop. So I should be looking or a xforce/magnaflow 2.5" 100-200 cell?

[nate92]

Yeah that sounds fine man

[djt]

ok thanks guys, also stainless steel or ceramic? And some Ive been looking at have the 02 sensor holes and some don't, which ones do i get?

Thanks heaps guys

[Jccck]

ok thanks guys, also stainless steel or ceramic? And some Ive been looking at have the 02 sensor holes and some don't, which ones do i get?

Thanks heaps guys

Stainless steel, not that much more expensive.. But will last much longer.

Well your O2 Sensor should be just before the Cat.. Somewhere on the Downpipe.
So you can either get one without a hole (Preffered)
Or get one with a hole, and get a plug from any exhaust shop/ebay

[djt]

ok thank you so much for you help and others