Convertor Mods

Not true. If horsepower is increased at the expense of low end torque, the stall speed could end up lower.
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X2. They don't call them a torque converter for nothing. Lots of Small block Chebies make a lot of horsepower at high rpm, but their torque curve falls off real fast. I always got a kick out of the Chev and Ford small block guys that never understood this. Try and find a 350HP small block chev or a Boss 302 Mustang with a factory installed automatic. 4 speeds only.