Aftermarket Throttle Body questions!

Its not cheap, but if you're getting an aftermarket piece I'd go with the Ford Racing one. Not too many companies make aftermarket TB's for our cars and the ones that do don't have the best rep for quality.
 
Remember that if you go bigger than 70mm, your going to have to open up the throttle body opening on the upper intake manifold because the openings on most of them are only 70mm. Depending what kind of power your car is spitting out, a 75mm could be beneficial.

Joe