I bought a Summit Viper XL last year and I love it. I made one change though, because the viper xls doesnt have a removable seat but has a seat that hangs down lower than the viper extreme, I got two quick release seat hooks from Summit and put them on my viper xls. Now I can remove the seat and it hangs down lower. Also, removed cloth covered pipe insulation because it started to retain odor and put new insulation on and wrapped it with split bike tire inner tubes. I left a bucket at a bike shop to get old inner tubes for free so I wouldnt have to buy them. This also works well to wrap the metal bars on a stand to quiet it.