The only place the performer is going to out-perform the Air-Gap is ON idle. How much fun will you be having in the car "on idle"??? Its old technology, the Air-Gap is a newer design that does a great job of landing in the middle of dual plane fuel distribution and single plane velocity. Theres literally no way you'll be dissapointed with it. Whereas the performer will leave you forever short-shifting a small block that wants to rev.

Bottom line: On anything other than a dead-stock rebuild, your machinist is wrong.