Two replies I’ve seen on here that bare looking at. First is the fuel pump push rod. I had this issue with mine. Only lost .125 but killed a ton of speed. Second is the turbo mufflers. Not a good choice for flow especially with a 500” engine. I switched from Pypes Street Pros to their Race Pros and picked up a bunch.

Bill


1968 Road Runner 383 727 3.91 8 3/4 3520 with driver 11.04 @ 124.26 with 1.67 60’
Done on G70-14 redlines thru factory manifolds New quickest ever 383 build in FAST.
10:1 451” replaced with 14:1 499”.