Originally Posted by TahoeM3

The problem is that the 4.8is isnt really all that much faster or more powerful in stock form than the 4.4i. I really wish the top of the line X5 got the 5 L 400 engine from the M5. THAT would be worth the price of admission. The 40 hp difference between the 4.4i and 4.8is is nothing comared to conservatively 105-135 hp that can be extracted from the 4.4i safely using supercharger, tuning, intake, and exhaust. You could do the same with a 4.8is, but the 4.4i is probably better for adding forced-induction becuase of its lower compression ratio. The N62 4.4i is a well-designed engine and there is plenty of room to extract more power. It's not like the S54 that is so high-strung.

Of course, then you get into the discussion of how much power do you really need in an SUV...don't really want to open that can of worms. But I say GO FOR THE SUPERCHARGER.