I ran the 645 last year in my maxx. Very nice for the money. Actually, one of the better non digital ones out there. This year, I am running the 5945, which is the digital version. I almost got the 645 again for the throttle brake servo, but ended up with a 5925 instead. The 645 is a 100% improvement over stock, and short of going digital, is my first choice in a steering servo.