I ran the MHD on my 13’ x35i with the N55 about a year ago but a the time they were working to iron out surging issues when accelerating from a stop. Ultimately the surge issues proved too annoying and they refunded my purchase and I removed the tune. I believe they have a new code set now that is better.

Of course after feeling more boost I had to do something so I picked up the home flash kit for the Dinan stage 2 tune and it has been great. It’s not quite as powerful as the MHD 1+ but it is stock like smooth and smogs without any issues. (Good value now too as I think it’s sub $500)

I also ran the VRSF boost pipe with both for peace of mind. I have no doubt the stress from the MHD would have ended the plastic oem pipe.

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2013 X5 xDrive3.5i Premium
2002 530I Sport Package
2001 X5 4.4i
2001 M3