Interesting! I have owned my XFire for 2 years now, have the Needswings CAI and no resonater, otherwise stock. I love this car and the only faster toy that I own at this time is my K1200S which is amazing. Last month I bought a 2008 535i with the sport tranny and the sport package among other goodies. Don't sell this 4 door dowager short, if you do you may be very surprised in a traffic light launch. On the drive down, I had flown to Savanah that morning to pick it up, I played with quite a few fellow travelers. On side by side roll not a one "left me in the dust". Can you take a 535i, sure you can but don't make a mistake on your launch or let it get too far ahead of you. Incidentally, the crack about 70 year old guys not wanting to play, this 71 year old will play anytime in or on any one of my toys.

Happy hunting.