Cataylic converter question?

SON240sx Automotive
1

Hey guys I have a question about a high flow cat for an s13. I need a cat with a 2.5" inlet and a 3" outlet is there such thing? I’ve checked Google but had no luck. The reason why I need one with that sizing is because aftermarket headers have a 2.5" inlet and the exhaust I could get for free has 3" so now you see the problem.

I know I could just buy a 2.5" catback but I’m trying to save money.lol

Or I could custom fab the header outlet flange to a 3" flange since I’m a welder:) what do you guys think.
Thanks

2

or just buy/make a 2 1/2" pipe fit inside a 3" pipe. just need to bump it up. easy as pie. do it all the time. could proably buy an adapter.

3

i’m haveing this same problem at the moment with my s13

4

^^^
post intro son. in new members section. this is not new members section

5

Meh, I’ve been using a 3" highflow on a hotshot header (2.5") for a long time now, works fine just get a good gasket. Its when you go from bigger diameter to smaller that you’ll run into problems.

6

^ true thanks man:)

7

I bought a magnaflow high-flow cat that is 3" inlet and outlet from PDM racing a couple of years ago. One side of it is bolted to my 3" downpipe and the other side is bolted to the stock exhaust which isnt 3". Maybe that one is compatible with all ?

Good luck.

8

Simply use a 3-inch cat and either weld a 2.5 flange onto the side that attaches to the header or just use all 3-inch. The 2.5 will seal to a 3 no problem. I ran this setup on my brothers car. Had DC headers to a 3inch cat which had a 2.5 flange welded onto it.