I installed my Mechtech back in July with several problems that I wont get into. But after Karl looked over the car he came up with his own solution to the problems that I had. First of all he removed three components that came with the original kit and programmed his own software to make more power than advertised. Please check the dyno chart, this is at 7 PSI on a mustang dyno.(dynojet will read higher numbers.) Also multiply that figure by 1.31 for crank horsepower on the dynometer. http://www.activeautowerke.com/dyno/97%20M3%20Mechtech%20vs%2097%20M3%20Mechtech%20w%20AA%20tuning.asp The Mechtech is a good turbo setup but AA is the best of course. You pay a higher premium but with the time and effort that Karl, Mike, and Fred has spent developing there system, you will not be dissapointed. They have worked all of the bugs out for a daily driver that makes big power.
If money is an issue, I recommend the Mechtech over any SC any day. You will get similar HP numbers but the torque numbers with a turbo just dont compare. I also recommend you get the software from AA. The OBD2 computer has a mind of its own and Karl only knows the puzzle to the pieces. Dont underestimate the guys at AA there knowledge and experience alone will amaze you.