We just reurned from out trip to NC which gave me a complete experience of the Dinan modifications(Mass air flow and stage 2 programming). The truth is if I had it to do over I most certainly would. The car performed extremely well in all the different terrains on the trip. I especially enjoyed driving up to flat top in Boone NC as well as Grandfather mountain(ski beech). There is considerable difference in the way the car pulls and accelerates all the time, but especially when put under demand. We live in Florida so it was a real nice change of driving conditions. I have seen a couple of negative reponses about Dinan and what kind of return you get power vs. cost. I feel certain now that I will go through with other mod's in the next year. Thats my opinion anyway. I know it's not a 4.4 X5, but it is a whole lot of fun for me. My wife was skeptical as well, but after driving on the trip and through the mountains she is covinced as well.