I saw an article about powerheads in fast fords and muscle mustangs about a year ago and those heads made awesome power, especially for the price. It was like over 30 something rear wheel horsepower AND torque, very impressive. I was thinking of going that route myself, but just like you i don't know of anyone who has gone with power heads.
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previous name: 84stangLX
'84 Mustang 5.0 LX
my LX
'89 Mustang GT
my GT