I have an new Big Gun EVO-X on my XR 650L i like it very well. i put 1,000 mile on it and the packing started burning out,i tryed to re-pack it with some FMF packing i had, with no luck.i called Big Gun and they hooked me up with a new packing kit. it will need re-packed every 20 hrs. or in my case about every 1,000 miles. : re-pack and re-tire. it is like 3 pipes in one, as it comes it has a quiet core/spark arester, you can pull out the quiet/vortex core and run it as a straight race pipe/very loud-opens bike up good,or run it as quiet-er with the spark arester in place, still with good power but more back pressure. my only problem is with haveing to repack,when the packing starts to go you know it- bike does not run as well and sounds rough.