Wondering how many guys have bought these and had problems with them opening up after you cruising along at 5000 RPM's and try to whack the throttle and it will not get above 6000 RPM's and your fuel mileage is horrible I am having this exact issue right now but if you start from a dead stop and hit the throttle it will blow right past my problem to max rpm my valves are not opening till 6800 rpm's I know this because I Dynoing my motor I am getting less than 5 miles per gallon at cruising at 5000 RPM just went out tonight with my son on the trail and road 56 miles and a 12 gallon tank was bone dry