I'm pulling the trigger on a Tune for the Z4M. The question is, which one do I get?
Bren Tune is cheaper, maybe by $100. Some forum members see +20hp on the dyno with just this tune.
http://www.zpost.com/forums/showthread.php?t=409785
ESS Tune is $795. ESS has great customer service and they make the only SC for the Z4M so they know what they're doing. Power gains are only 8-10hp, half of the Bren Tune.
I have mods on the car and want to get the best out of them which is why I'm getting this. I track the car every other month and autocross every month. I don't use the sport mode at all because it just shortens the throttle. I need the full range of the throttle so I can feather it while driving at the limit and sport mode would just cause me to take it into the wall. A tune that can fix sport mode so it gives me instant responsiveness but doesn't shorten the throttle would be great!