Hey, I need a cat to pass safety so I am going to buy a high flow magnaflow cat.

I have a 2.8l right now so im not extremely worried about affecting the performance.

My stock exhaust is 2.25" i believe and I want to buy a 3" high flow cat and just use reducers to hook it up. I want to buy this cat because eventually I want to do an engine swap to an ls1 with 3" exhaust.

So what would be bad about buying a bigger cat and using reducers??? should I just go with a 2.5 or 2.25?

thanks

 

Please help. I cannot find any info on this. I searched google too

 

Who would be doing the adapting? If you can do it yourself, have all the necessary cutting & welding equipment, then maybe.

If you have to pay to have this done, just get a direct-fit cat.

 

i have a welder and grinder. Ill be doing it myself

 

I've seen 2.5" to 3" adapters, but not 2.25" to 3". You can always have a shop expand a piece of 2.25" pipe for you, though.

What I would tend to do would be to buy direct-fit '86-'90 TPI single cat cat and cat-back parts, then adapt the cat inlet to your existing Y-pipe. Then you'd be ready for the LS1 when it happens (getting a Y-pipe to the stock cat inlet location isn't quite as straight-forward as it is with other engines, though).

 

Would what you said with that cat back work If I will be using long tube headers when I get the LS1?

 

You'll have to snake the pipes back to the factory cat inlet location. The long tube collectors exit at about the same lengthwise point on the vehicle that the cat inlet is. Makes it difficult to get the pipes back over to the cat inlet.

I don't know how much you've researched this, but the LS1 swap LT's and auto transmission don't play very well together. I'm putting the parts together for an LS1/4L60E swap, it didn't come with exhaust manifolds. I'm planning on BBK shorties, will require custom pipes to mate with the existing exhaust system.

 

I'm planning on a manual tranny. Probably the t-56 any issues there?