I have a 3.0i and I removed the resonator and put in straight pipes..I already had the supersprint, so now my car sounds like a monster. There are no sensors involved anywhere near the resonators.. so there is no problem removing them... but for the V8's I think people reccomend putting in the X-pipe instead of straight pipes...but the cost is very similar...go for it...it will prolly sound amazing!

__________________
2010 BMW X5 ///M
Silverstone Metallic
Black/Black Merino with Black Piano Trim
Premium Sound
Driver Assistance
Comfort Access
High Gloss Roof Rails

Gone but not forgotten: Upgraded!
2003 BMW X5 3.0i
Titanium Silver
Navigation
Cold Weather Package
Premium Package
Heated Steering Wheel
20" wheels (275/45/R20 all around)
Supersprint Magnum Exhaust
AFE Cold Air Intake
Bimmian Chrome Guage Rings
What's A Resonator?