Just installed my ulmer stage 2 clutch kit very nice kit, install in about 20 mins, i drag my friends stock rx1 just before the install, raced 6 times, then install kit and then raced again,6 times - 5 sled lengths gain each time, my sled 06 rtx is stock with 10 spark plugs and a gutted muffler, loved the kit, my friend with the rx1 is ordering his kit today, very easy kit to install goodday