I received my MM3 from Ray Wednesday and installed it. The exhaust came later so I haven't had time to install it. Ray did advise me to not drive it too much with the stock exhaust though. I do have to admit, initially I wasn't blown away with the 60hp ecm tune. That's as high as I had turned it up since I still have the stock clutch in it. I have driven it a little more since the initial drive and can definitely tell a very noticeable power increase. On my way home from dinner this evening, I ran it on the 90hp tune. WOW! Such a huge difference! I will order a clutch next month so I can see how the bigger tunes feel. Ray and JJ were very helpful and polite dealing with my diesel newb questions and sometimes poor reading comprehension. I can see how this truck stuff can be very addictive and expensive.