Reggie's Motorwerks in Noblesville (north of Indy) has done a dozen or so. I'm about to talk with their head tech about details.....
https://g.co/kgs/ewYywR
They use the Bimmerworld pack with ARP bolts.
Ask for Nick Sartor- nice guy and knowledgeable ...
Tell him Mark C. sent ya
(By the way, they support the Hoosier CCA chapter)