convert2diesel,
I agree with what you are saying, I guess all I was getting at with the motor mods is that theoreticly some gain can be had from going into the motor.
grape,
Idealy the car designed for max fuel economy won't take that much HP to push through the air so in reality adding a turbo may add a parasitic loss on the engine by restricting exhaust flow. The only time adding a turbo becomes effective is when you have more fuel than air, and in this case I don't think that will be an issue... Sounds like your stuck in the world of big HP racing to me...