Hop Up Kit; GX240, GX270, 9/11hp OHV, & 301; Stage 1 Our Price: $52.38 Engine Kit, 263cc for Tillotson 76mm Block, Stroker Kit Our Price: $273.00 Hop Up Kit, 212 Predator Hemi, Stage 3 Our Price: $315.00 Hop Up Kit, 212 Predator Hemi, Stage 4 Our Price: $494.00 Engine Kit, GX390/420, 420cc, +.200 Billet Crank, 88mm Forged Piston Our Price: $923.00 Engine Kit, GX390/420, 440cc, +.200 Billet Crank, 90mm Forged Piston Our Price: $894.00