Tweeter have had my MINI for three weeks now, while I was on vacation then working in Canada. Drove up to Nashua this lunchtime to check out the “improvements”.
Engine noise JUST AS BAD; at “normal” listening levels (where you can still talk to passengers) the engine whine is uncomfortably intrusive at 2500-300rpm. At higher volumes you can’t hear the whine, except in the gaps between tracks, but I guess it is still there hurting my ears because I get a headache really quick.
Tweeter claim to have tried everything including new HU, amp, wiring, etc, etc, etc. They say nothing helped. They are currently trying to blame the Lojack system suggesting that the noise is coming from it (“was it installed properly or by a cheap installer”) – I don’t see how engine rev noise can be emitted by Lojack. A continuous hiss, maybe, but don’t believe that Lojack transmits RPM signals …
Tweeter also said they have improved the overall sound quality – maybe they have, but it still does not “blow me away” or impress me as if it is worth $2000+ that it cost me. I now have no faith in Tweeter to improve anything … I have left the car with them to rip everything out that they did and put it all back to HK amp and speakers.
What a painful experience.
Advice for others: Go with someone that can prove they already did a system like you want on a MINI.
M&I / GBMINI 
I wonder if this MINI2 thread would have helped to eliminate the engine noise from Tweeters install …