[vector1]

considering each primary should prob be 2" on something that big and you're running 4 cylinders through one 2" or 2.5" pipe, i would think would be restrictive.

if the transition from collector to muffler is not smooth there could be some reversion there also.

like 392cobra said, if your convertor is loose your motor would rev but not accelerate, if it is tight you could be bogging the engine down at lower rpms, but something that big should be able to go through a set of tires pretty quick.

considering your complaint is at 3500rpm where the engine wants to breath....., and at that rpm your convertor should be pretty much locked up.

at 3500 rpm with your tq and hp you should be able to get sideways pretty easy in 1st or 2nd gear, prob 3rd gear also.