I just got some Hedman headers and y-pipe, and I have a Dynomax catback ready to go on also.. and I want to make a dummy pipe to go where the cat would normally go (using 3" pipe with a cat-style press-on connector type thing..I don't know exactly what they're called), but I need to know how long it should be so that everything follows the stock routing as closely as possible.. I have an '84 Camaro if it matters.

Thanks in advance.