If you take a vote on this forum, it will be unanimously BPM. Period. I've put off getting a tune for over five years, because I was not convinced a tune would give you any gain or added driveability. This was purely based on my experience with DMS when I had my E46 M3. It did nothing to enhance my driving pleasure.
After reading a lot on this forum, I was finally convinced BPM offered something different. I am a convert now ... just the entire process beginning from enquiry to the tuning ... it was top notch.
I did approach Sal, and he gave me all the information and pros and cons. He never once criticise any of the other tunes offered by various vendors. He refused to comment when asked as to how his tune was different from the rest. Same goes to Mike.
Ultimately, I made the decision to go with Mike. I am happy. Same cannot be said about other vendors. Some vendors failed to return my enquiries. Some were not forthcoming with the information. Neither were they critical of the other tuners. Looks like there is a common respect for one another amongst the tuning fraternity.
I exchanged close to 15 PMs with Mike before I finally decided to go ahead. In addition to a good tune, you need professional and polite and informative customer service. Mike gives you that. You need to give credit, when credit is due. That's what I have done. Call me bias, I don't care. I am happy.
E92 M3 2007 - ///PE with Test Pipes and BPM Stage II; CF Interior & Splitters; CIC with Connected Drive