You will need the G2 throttle tube as well as the cam, 300. 400 etc. The small cam itself will not fit on to the stock throttle tube. KTM Twins sells a throttle tube that has the 400 cam without the outher cams for about 80 bucks. The preload adjuster comes with instructions and is easy to install. You will have to remove the shock, and will need a good spring compressor to instal the adjuster to the shock itself. Hope this helps... And Happy New Year.