I had the P1 on my 300SRT and until it broke, loved it. Car was fast and run 11lbs of boost. When I sent it for rebuild to ProCharger due to the price only being slight higher I went with a brand new D1. Took the car to Arringtons; they called a couple days later and told ME that the car was a HOSS and first dyno with the small pulley was right at 800RWHP and recommended for street driving to put on my larger pulley, lower boost, retune and see where it was at. 2nd dyno was 740RWHP, they called ME again and again recommended a third larger pulley and lower boost again.... this netted 663RWHP @ 13lbs of boost; a safe steetable boost I was told. Problem I'm having IS: I cannot full throttle the car, it immediately goes into limp mode. At half throttle, very powerful BUT... it will NO LONGER go straight ~ FISHTAILS BADLY ~ Also the car mostly stalls and shuts off 80% of the time when put into reverse. Start it back up; have to wait for transmission to kick in and then I can back up. All in All; It's OK.... but certainly NOT perfect!