Hi. I am going to build a 350 to put in my son's 1964 Chevy C-10. It will have a "lumpy" cam put in, as we all wanted when we were young, headers and all the good stuff. But here's what has me puzzled. Is 3" exhaust pipe a bad idea? I have heard that it is good and also that it is bad( no back pressure). If someone can set me straight I would really appreciate it.  

I recently replaced my 3" mufflers and tailpipes with 2 1/2 on my 67 chev p.u. with a 427 big block.But I left the 3" from the headers that go thru a x-pipe then reduces down to the mufflers.At lower rpms it's stronger than before and really not much taken off the topend.I think now the 3" section has a better boundry seal which creates more velocity and pulls it out of the headers faster.Just like putting to big of cylinderhead intake ports on a engine.Run 3" at least 12-18" off the headers with a balance pipe or x-pipe and 2 1/2 from mufflers back.I love exhaust, I've spent alot of money changing it over the past 29 years on my p.u.   WIEDER