NFS engine sounds are blown out of proportion. Every car in the game sounds like something out of "Fast and the Furious". The GT series have loads of stock cars and the engine note is directly recorded from the real thing.
Give it some time n you'l get used to it.
BTW, you could disable music in GT4, i'm sure GT5 has that option as well.
Drifting again is far more diff on the GT series. It can be done but needs a lot of practice. It always helps to have a steering wheel instead of a PS3 controller.
YouTube - Short Ver : GT5 Prologue Drift Day practice session BMW M3
Shan2nu