SLAMMEDM3 - I had my ECU reprogrammed and I love it. I had the car dyno's and I did gain about 30hp. The shop said I may not feel the difference however I do feel the difference in Torque. That is the biggest difference I feel. At lower end RPM's the car is more responsive and doesn't feel as slug ash as some people talked about when they first owned the car. I also have new pully's and an exhaust.
I used a local guy in Arizona. I did consider Active and ESS however I wanted a local person just in case there was an issue. I paid $1,200 and I would do it again.
The Verdict: Every other manufacturer should give up on building their own cars and just make M3s instead. -Car and Driver June 2008