I've seen lots of 4V/fox swaps, never with the TB in the back on the intake, not sure what you are referring to...
Using a Mafia for what you want is not an option, you really need to fix the issues with the leaks first.
Mike Litsch
Powerteq Customer Service Manager
Diablo Tech support by phone:
561-908-0040x4
M-F 8:00 AM to 5:00 PM EST