ignore this guy , he may have a nice bike but he doesnt know about dt's . its more than possible to get 90 from a dt . i ride a dtx im 6 ft 6 and wiegh 14st and mine does 85 mph without a problem . the speedo de-restriction is the easiest to fix . coming out of the speedo there are 3 wires going into a connecting block and 4 wires on the other side . find the black wire on the side with 4 wires with a green stripe , snip it , add an extended piece of wire to it ( long enough to earth it to the frame ) this will stop the engine retarding at 8,000 rpm and will rev freely up to 10,000 rpm . next step is to get a new exhaust , DEP exhausts are the easiest to find and is what i have on mine but , an arrow exhaust will work just aswell . the bike will do 85 easily now , if you want more you have to start getting techy . look at possibly getting your CDI unit chipped or upgraded and then look at changing sprockets , cams , jets and carb . hope this is a lil more helpful than negative nancy's offer =D