All I can say is wow....There is a big difference between the two. First I installed the dyno..easy..very easy. Tested it. There was a power increase throught the power band.. It is worth it if you don't want to mess around with the air box and want a little more pep. Installed the the Airforce kit...I must admitt I was first leary of cutting up the air box. Installed the kit, it took about 1hour 30min. Tested it. Big power gains for a jet/air box kit combo. The nose will climb to the sky in 1st,2nd & 3rd. Conclusion...I hate brass screws..alot....The airforce kit is worth all of $99.00 us dollars, it just rips. If you are looking at max performace get the airforce kit. I haven't had a chance to drag any other quads because my weep hole is again leaking coolant(sh$$) I will post pictures of the air box in my profile...You need too cut the box and the lid for more air. By the way this is just my 2 cents and letting other Predator owners know about products out there. Next on the list is a Rath Racing seat cover and hydro clutch also from Rath.