early A body exhaust EXPERTS!

If you are set on duals as other posters have commented, does not really matter for performance where H is placed. Definitely consider trans. clearance issues. My 65 cuda has a custom fabricated H-pipe dual system. H-pipe feeds off of fenderwell header,s & the H is right past collectors putting location just to rear of trans cross-member. I race my cuda occasionally and as Scamp stated did not want to deal with total exhaust removal if trans had to come out so this just leaves a little tail shaft over h-pipe. Went extra mile on mine and added flex section as the H so it could be removed. Setup works awesome but my 340 is also seriously modded. Have had tranny out three times with no exhaust removal which saves a boatload of time.

Oldschoolcuda