I bought a set of 1 5/8" - 3" hooker headers, 3" cats and 3" mufflers. But now looking back I realize that a 3" exhaust is too big for my engine (305). I want to connect the pieces with 2.5" pipe. My question is: can it be done? Is it difficult? And will the exhaust hold up when I drop a 350 with around 350hp in the car?

 

bad idea, don't go from big to small only go from small to big

 

3" is perfect for your 305. I would return the muffler and get a complete cat-back kit tailored for a single cat TPI car.

 

Im having the exhaust custom done. The guy I bought the car from had 2 pipes running from the headers to 2 cats then 2 mufflers, but the pipes never connect. But why use an exhaust from a tpi when I got a 4bbl carb?

 

TPI systems a full 3" without any reducers attached to the end of the I-pipe. The TPI systems are tailored for a 3" cat whereas the other V8 applications are reduced down to 2.25" so you can keep the stock cat.