If you're looking to build some type of stealth vehicle, you're M3 drivetrain might be better served taking residence in a 325i touring model. Ben Liaw at Rogue Engineering did such a conversion, not only swapping out the drive train, but also the complete interior. Despite the fact that the swap took place within the E46 model line, it was still a very difficult swap for Ben and his team. If what the guys here are saying isn't sinking in, call Ben for his opinion. He'll give you the straight and skinny on whether or not the M3 into X5 swap is doable.

At the end of the day, I already own an 04 4.4 with my 06 3.0 6 speed due any week now. I'll leave the slushbox to my wife. I had to fight with my dealer to get the 6 speed. Now that its upon me, I've already got my mind thinking about the possibilities. At 260lbs of torque on the S54 (which is readily available in Los Angeles) this is more than our stock 3.0's, is it not? As for supercharging...I suppose...I know this is the cheaper route. But I'm not a fan of artificial aspiration. As for getting a 3 series touring...I saw that car that Ben did. A small wagon is not my thing, but I can appreciate what went into that project. I may end up doing nothing altogether, but I'm already giving it some thought.

the 260 ft/lb is way up there in the rev range. for something 3500-3600 lbs, it's good.. for the X at more than 1000lbs heavier, that's a different story. Curious why you're not fond of forced induction?

Sanguru...I know that mild super/turbo charging isn't necessarily harsh on the engine. For me, it is just a preference. I'd prefer boring, stroking, honing, valve grinding, uprating camshafts and the like...At the end of the day, I just wish BMW had chosen to offer the 4.4 with a 6 speed manual.

Actually I believe there is a guy on E46fanatics, MITE46 (did a 323i- M3 SMG Conversion) who wants to do the same conversion on an X5.

I would love it if the 4.8 had SMG i would def have gotten that.

Considering the X5 and M3 have existing simultaneously for the past 6 years, somebody would have done this swap by now if it was such a good idea.

My suggestion to call Ben Liaw is still reasonable - he's done swaps and he's a fabricator. If anyone knows how to make this job come together, he would. My bet is he'll tell you that the biggest hang up will be the harness.