our shop sold only SLP cuz that's all we knew about at that time and over the seasons I came to the conclusion that ; put it back to stock or it's guna blow up, now seeing all the pics of the FNI I would recomend only that one. While the SLP if properly installed worked fine we replaced every boot and if they hit any little thing and opened the seal all the belt dust went right in on the reeds and rod bearings and down she goes, as sais clutching and balance is critical on this poo mess.