ok right now i have hooker headers sitting in my room...anyways i have 2 1/2 inch pipe from the cat back to a flowmaster (flowmasters and pipe no more than 3 months old) anyways when i swap my headers on will a 2 1/2 inch y pipe be enough? do i NEED 3''? i heard a single 2 1/2" is plenty for me right now if it is im not gonna mess with it yet but also i wont be running a cat when i stick the y pipe and headers on. i dont wanna ditch what i have right now unless it would help alot which with the crap heads i doubt i need anymore flow...

 

2 1/2" should be fine, especially for a L03 with stock heads. I pretty much went the same route as you. 2 1/2 flowmaster, with a 2 1/2 highflow cat. I decided to go with the 3" y pipe however, when I came to the realization that the L03 was not going to do it anymore, and I would need it for my next engine. I wish I would have realized that before I went with the muffler and cat!!!.

 

see right now im not sure what im gonna do im considering getting a second car this summer but keeping the camaro of course...id like to either find a l98 91-92 camaro or a mustang i know i know but i kinda like them and they are decent cars

 

Well, we both have the 305 TBI. It is very reliable and will last a good amount of time. It's slow though. And the only way to make them reasonably fast in the quarter is to basically replace all the main components. I plan to drop a 383 stroker in there, hopefully using a holley 670 TBI.....though I've read that it may not support the 400+ hp the engine will be able to pull....I'll have to find out.
Anyways, what i'm getting at is........try a faster camaro before going mustang. I'm not saying anything bad about mustangs, but if you're like me you love your camaro, even if it may not be that fast right now. Now imagine how much more you would love it if it were able to pull up to a 2000 GT in your third gen and just smoke him.....I've seen it done and let me tell ya, it is sweet!!!! But it wasn't a stock L98....

 

Do you think my stock 2.5" intermediate pipe is restricting my engine. 305 TPI w/crane 2032 cam, 1.6 RR, siamesed base, edelbrock headers(slightly ported), high flow 3" cat., my car was running a 14.6 at 96 mph before the cam/rollerrockers. I don't have a real time yet but G-tech was at best a 14.3 at an est. 97/98mph. A little disappointed.

 

I answered this in your post.

And as to the original post, a cat-back wouldn't hurt, may help slightly, but with your HP you don't need it, but hey it'll be there for the future, plus your car will sound better.