Try a mid-range setup. Go with 21-24 gram sliders and the torque spring. This will give you some top end. Then try a larger carb. A 32 mm pumper will give you the power you need to move the sliders with any efficiency.
just call any of those dealers, Glade (doonrunr) at edge powersports, Tom (Kidnme) at Kidnme karts, or Eric (BIGE) at mcdonough powersports... They are all awesome and all can help you out!!!!!!