I am currently building up a 350 to swap into my car. I want to put headers on it, but don't plan on upgrading the exhaust until later. Will this be a problem? If I put on headers and a new Y-pipe, is there some type of reducer that I can use until I change my exhaust from 2.5" to 3"?

 

You know why the put a cork in a bottle to keep stuff from flowing
out. Well thats what you are doing to the exhaust putting a cork in it.

 

Get the headers, an exhaust shop should be able to fab up a pipe for you. Unless you're building some serious HP that stock cat-back won't be all that restrictive, and headers will still help a lot.

 

Well, I can`t afford to upgrade the exhaust now, since I am spending all of my money on my engine. So I`d have to get a custom peice made. I eventually want to put on 3 inch exhaust. I just thought it would make sense to add the headers now, while the engine is on the stand.

 

That would be the easiest.