52mm tb or 58mm?
 

Which tb is best for a heads and cam app? 58mm 0r the 52mm. Correct me if I am wrong, but the 52mm is good up to 500hp correct?

If you got a stock displacement with heads and cam, then a 52 should be enough. I cant find it, but there was a calculation to find out what size you would need.

Goes something like:

Cubic Inches x RPM / 3456

383 spinning 6000 needs 664 CFM, but gotta add more on or something.

Do a search on THROTTLE BODY, the 12 pages of results should help you.