DO ALOT OF HILL CLIMBING AND SOME TRAILS, WHICH ARE VERY TIGHT. QUAD IS STOCK ENGINE WITH EXHAUST AND 2 IN 1 CARB. LOOKING TO UP THE QUICKNEST TO THE POWER BAND AND QUICK RIDING IN 2. NOT SURE THE DIFFER IN CHANGING THE FRONT OR REAR SPROKET? DO I CHANGE JUST FRONT, JUST REAR, OR BOTH?