My bros picco 12 blew it's conrod, so he's getting an OS 18 TZ turbo, I saw a video of a XXX-NT with that engine making like 55 mph, and still having enough torque to wheelie at about half throttle. I sorta want one for my XXX-NT, and my mach 15 runs great, for a mach 15. I could almost garauntee it's an airleak though, my bros Nitrostar 25 in his savage did the same thing, the exact same thing. I just went to napa and bought some copper RTV, and sealed the backplate and around the carb, and now it runs great!