If you are into smoke systems on your planes and you have not tried these mufflers you are missing out on the WOW factor. By far the best combined sound, longevity and smoke density out there. Check out some of my online freestyle videos and see what you are missing out on. I have been running these mufflers since 2009 on 100's and 120's. There are several muffler choices out there but there must be a reason Desert Aircraft goes to Slimline for the manufacture of all of theirs! In fact that is my old Aeroworks 260 on the home page of DA flying a low speed knife edge pass. Check out the smoke even at low throttle!