revert back to oem manifolds?

i'm looking to do just that..

the hedman headers are a pain as they take up all the space in a A-body.

right now i can't access the starter that will need work sooner or later and i can access the oil pan and it's leaking a little..

Would i see a significant diffrence in performance? the motor is almost stock (aftermaket intake and carb is a AVS.

what would be the best OEM or aftermarket exhaust manifold ? no more long runners.

i assume something coming from a 340 would be good ?
Author: fr0st