I had reasonably good results with exhaust mods.
I had a stock 55.1 235, 81 RWHP.
I changed to a Corvette exhaust manifold & twin 22" Smithy's mufflers, 87 RWHP.
About a 7% improvement.
Dyno Results

regards,
Leon

Last edited by Leon; 01/16/2012 5:47 PM. Reason: add inch sign behind 22