Does size really matter?..the stock Y onmy 305 non-HO is tiny..I'm going with headers, but am undeceided on the Y pipe size. i know they put on small tubes for low end torque, but can't we have a compromise size for HP too? when does size become negative?....21/4", 21/2", 23/4"? Does anybody out there know? i'm supposing the collector will always be 3". thanks guys

 

Most aftermarket headers have 2 1/4" to 2 1/2" y-pipe. I don't know of any that are larger than 2 1/2". The size of the y-pipe will not matter as much as the size of the catback.