Do you have a stock throttle body? I noticed you didn't mention that. Thats a MPH atleast there.
Also what are you cam specs. The performer intake makes peak power around 5500. If thats a higher revving cam, you should go with the RPM upper.
Also where are you shifting, and playing with the shift points can gain a bit more mph.
I have run anywhere from 16-21 degrees initial timing with my TFS TW heads. I know you have more compression, but definatly try 16, with 40psi w/ the vacume off.
Play with it from there.
SKy
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-1989 Saleen Mustang #406-
TFS TW Heads, E-303, Edelbrock intake, 70mm TB, 73mm MAF, 24lb injectors, 1 5/8 shorties, Off Road H, 3 Chamber flows, Jaz Race seats, Back seat removed, sub-frames, Roll Cage, and a 80 shot of N20.
12.54@107.4 Motor
1.69 60'