[kpgray]

I installed an MPPK and MPE in May of this year on my 2014 335i M-Sport (late build 6/14 model) with about 12K miles on the odometer. I presently have just over 15K miles. When I first installed the MPPK and MPE I did not notice much difference other than the sound was slightly louder. Initially I was disappointed, however after each tank of gas I noticed the car started waking up. After about 1K miles on the upgrade the car has risen to new level!
The exhaust sounds as it should and in sport mode the burbles are audible without being obnoxious (at least to me). The performance has picked up where I felt the car lack as stock. The car pulls all the way to 7K RPM with increasing power where before the car seemed to level off in power without much gain from 5.5K to redline. Although the two systems claim 41 HP gains (35 HP for MPPK & 6 HP for MPE), it is a real feel where you want it, the mid range punch pulls much harder and keeps gaining to redline, and now the exhaust backs up the punch!

Pros: Performs the way one would expect a BMW to. Exhaust is deep, very nice burble and crackle when in performance mode. Almost no burble and crackle in eco-pro mode. No drone when driving high speed for any distance. Exhaust draws attention. Mid range torque pulls hard for regular commuting. Engine continues to pull hard all the way to redline (real feel in increased performance breathing from 5,500 to 7,000 RPM). Un-noticeable change in MPG when driving comfort mode.

Cons: Cost is rather steep for 41 HP ($3K+ or $75/HP). Louder exhaust does draw unwanted attention from traffic enforcement. Tendency to drive in Sport mode reducing MPG.

Overall, it is worth the buy, especially if you have your vehicle under warranty. I would recommend that anyone purchasing new, incorporate into your purchase from day one.