Re: 300 $ to blow on a china girl.....
Shifter kit and appropriate running gear.
40mph flat ground with a 44t is pretty good. Think what you could do with a shift kit.
2 WHEELS: '11 Huffy Good Vibrations, '11 Skyhawk GT5, 44t, CNSV2, NGK BPR7HIX, Bosch wire, shutupexhaust, 26x1.75kevlar tires, Tektro C230's, new stupid Bell chain