We sell Gruppe M and besides the 10 or even 15 hp gains , the satisfaction of customers , from the moment they receive the Gruppe M CAI to the point where everything is installed has been stellar. It is amazing how everyone has been so happy with the purchase.
The quality of the CF and the fit and finish are amazing.
I do agree that it is not for everyone, but it has been very popular for us.
BTW, we are thinking of doing a GB for about $2200, if anyone is interested.
Let us know.