Just talk to Kelly at KMS Performance and he told me that with the STM clutch (properly tuned) he gets 8 to 10 hp more to the rear wheels. That is very similar to what I got on my mod commander when I switch to the stm on my built motor. Guess what? I'm getting an full STM rage 6 for my Maverick. He also gets a couple hp with his cat delete kit as well.