Not if its done properly mate. I had suspicions my 320d was mapped before I had it, found out recently it was!! Caused me no problems mate, just tonnes of torque and high mpg Gav the happy
The woosh is normal when letting off the power, this is similar to a dump valve in sound. BMW's do have heavier steering, and my 320d had 18/225's on and the steering is certainly heavier than when i had the 16's on.