I got 13RWHP/12RWTQ increase with my Diablo on a Mustang Dyno. The MM SFC's seem to be the connector of choice. If your really into lower gearing the choice seems to be 4.30's for 5 speed and 4.10's for Auto's. You'll gain 10RWHP with a Mid-Length Bassani header, but Long Tubes will gain you 15RWHP. A CAI will gain you 5RWHP no matter what other people say, and it looks way better than plastic stock crap. You can opt for one of those Maziere electric water pumps. Those are supposedly worth 6-7RWHP. I'd stay away from the bigger Throttle Bodies if you ask me. They're hit and miss in the Mach engine.