Sounds like the headers are an extremely cost effective power upgrade on that combo.

Quote:
The engine did not like the ex manifolds at all


They never do.
Some just dislike them more than others.

650hp in a 4000lb car should be able to run 10.60’s at 124+.

68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads