I'm using a spec stage 3+ on my 7M and love it, however I have found the limits of its performance. I was at ~400-450hp last year prolly with ~380ish tq (never dyno'd, just guesses based off of current nubers) and it couldn't hold a no-lift shift at redline if the tires gripped, so bear that in mind. Its rated for 630tq and it's held 480tq minimum without noticeable slippage (just accelerating) as far as I can tell. Just the drag style shifting gave me problems
I will be going to a spec P-trim twin next year so I should have feedback on that arond this time next year!
Also of note- I've driven a BPU mk4 with a fidanza/rps3200/heavy single and all I can say it was possibly the worst setup I've even encountered!
The customer agreed so we put an RPS carbon/carbon twin disc in the car and it was the exact opposite. I have never driven a car with engagement that nice which stood up to the abuse that kid dished out to it.