[super_kit_car]

it really boils down to how you are going to drive the car. if you will be doing a lot of street racing and not a lot of 2 hour trips, I would use the bigger cam. if you want to be able to go anywhere your heart desires, I'd use the smaller cam. the bigger the cam, the more maintenance you will have to do to the engine and less drivability. you also have to consider suspension modifications, to put the power to the ground. I do a lot of street racing and build my engines barely streetable. the longest trips I take are for about a hour. my mustang has a .640/306d comp cam, it sounds nice and with good port work it puts out plenty of power. a lot of guys like comp cams for fords. I think they run well in fords, but that's only my opinion. some guys around here have .700 lift cams, and they drive them down to racewaypark to race, and drive them back home, although like someone said earlier .700 lift cams and above are hard on the valvetrain.