You have absolutely nothing to gain with that swap with your combination except losing bottom end and throwing your money away. Other than that, go for it..
The edel heads match up with the gt40 intake real good flow wise. I cant see you gaining anything witht he new manifold, and I had both TB's, 65 and 70mm. The 65 is better, more throttle response, and no loss up top.
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1993 GT/AOD
'93 Mustang GT