I personally prefer the 4.6is because of the relative simplicity of the M62tu compared to the mess that is the N62. Chain guides might be tedious but they're easier than replacing 32 valve stem seals. If you try to do the valve stem seal job with the engine in place it's horrible, and if you pull the engine to do the valve stem seals then it adds a whole lot of extra labor. You don't get all that much extra power with the 4.8 anyways.

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2003 X5 4.6 | 2000 540i Touring

Formerly owned:
2004 Range Rover | 2000 M5 | 2000 540i/6
1995 750il | 2003 Mercedes S500 | 2003 540i/6