Hey guys right now i have a mostly stock 1989 camaro rs 305 tbi. The only mods are a flowmaster catback and an air cleaner. I want to add a couple of more mods that will still be usable if I end up putting a 350 in it. Im thinking of putting headers and an aftermarket y pipe on it. Any good cheap combos? I saw summit racing has some of their own brand headers and some different y pipes. All the y pipes have diff flange set ups, not sure which work best? And how much louder and more performance will this help me with...anything noticible?

Most headers are 1 5/8 primaries. They are good for a 305 and OK on a very mild 350. But if your plans on a 350 are for real, get a set of headers with 1 3/4 primaries. There are shorty and long-tube designs to fit our cars. But the long-tubes require more work to get to fit up to the stock cat-back. In headers you get what you pay for. I had a set of cheapo non-coated Headmans on my car when it had the 305. They worked well and fit well, but were bad about leaking and blowing out the gaskets. Get a set with THICK flanges to prevent gasket failure and warping of the flanges. The 1 3/4 SLPs I have now are awesome. Expensive new tho. There are other brands but the good ones cost $$.
Performance will definately wake up even the stock 305. Read up on the long tune vs. shorty power range differences.
Loudness will increase but not that bad. The tone will change too and be more pleasing IMO.

also it depends on where your powerband i beleave the bigger primary's = more torque at the low end