Thinking of exhaust mod

FWIW, Summit sells cross-over kits. You have to hope it'll line up nicely, and they bolt in w/ clamps.

Also, this link is to the best exhaust article I ever read. David Vizard writes some good stuff.
http://www.superchevy.com/technical/engines_drivetrain/exhaust/0505phr_exh/index.html