im in the market for a black on black x5 i have found alot of them. im lookng for one so i can put a nice set of wheels on it. ( stagered ) my question is that i know i want a v8 but are both the 4.4 and 4.6, are they both good engines? and i know i want navigation, but herd the bmw navi not all that good. so ill prob get a double din aftermarket to install. what do i need to look out for and look for when getting a used e53. any info will be helpfull. i have owned alot of bmw cars and this will be my first x5. thanks..