It depends on how good you are at jetting and maintenance, although IMO the PW80 is pretty low. My 8 year old brother's PW80 has a filter and is jetted right and is pretty fast with him on it. The suspension is a little outdated but it actually does alright with his weight. The TTR90 is taller and heavier, but is 4-stroke if you like that. The PW80 is pretty on par with the TTR90 noisewise, neither are really loud although I haven't measured them or anything. The PW80 has a restrictor plate you can put in the exhaust also to limit the power for a beginning rider. They are both auto-clutch so no worries there. The PW80 actually has a 4-stroke like powerband, no real hit and good torque throughout. My brother likes it a lot and I think it's kinda fun too so......bottom line, IMO if you don't have a problem with 2-strokes (heck, the PW80 even has an oil injector!) get the PW80!