Okay, you have your idle...and you have full throttle...nothing in between no happy medium no nothing and it's loud as all get out. You spin something like 15600 full and 3k idle. See, the Knife from what I've been told likes mid range stuff, you rarely fly it at full because of the throws you have with the surfaces that and you don't need full for 3d flying. So you're left with a pipe that'll haul butt but won't do what you need it to do for that plane. If you want it, and wanna save money I'll give it to you CHEAP like 15, 20 bucks...box it up and ship it your way. But for 50 bucks it is sooo not worth it. I'm running stock muffler now and it's quieter, there's a highly noticable improvement in midrange and I honestly can't say I noticed a huge difference at full throttle. The minute he hears you have a 46fx he pops out, oh you need this header and pipe...horse crap. Just my 2c.