Well if the RMS kit is more aggressive per Happy, then I would hesitate not one bit to run the ESS kit on my M54. The transmission will outlive the motor easily, and the M54 is already pretty bulletproof.

I'd rather have a kit more conservative supercharged M54, that I could daily drive and not worry about it, then 20 extra hp. Go on bimmerforums and search for ESS supercharged M54's, you'll find their reputation is excellent.

If money was no option I would do differential swaps (to get rid of the manual's 4.10's), a 4.6is body kit, and ESS supercharger and drive it until I retired.

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2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards