i have 5mm on each of my fronts to clear the brakes on the s4. hub centric w/extended lug bolts.
Havent had any issues with them, but i don’t know how i would feel about running them hard or on the back of a RWD car (dont think they would ever see the M). just something about them doesnt seem 100% safe.
i have the adapter type that bolt to your current studs and have their own for the wheels. they were 60 a pair from ebay. i have 1 1/4 in front and back, also my dad has been running 450rwhp thru his for 2 years now with no issues