I also agree with Unit. You can make impressive power with the stock cam. It is about the very last thing that needs to be changed.
My friend and I built his 91 coupe. Stock TFS heads, Cobra intake, exhaust, stick car, 3.73's, etc... and a stock cam. He ran a 12.50 @ 108 on slicks and an 11.9 @ 114 on a 75 dry shot.
In my opinion, if you put in the cam with no other major work you will have a car that is a lot slower than it sounds.
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1988 Mustang GT
11.8 @ 123 (7/14/01)
1992 BadAzz Wrangler
1993 Explorer
See my car at:
www.mustangworks.com/cgi-bin/moi-display.cgi?179