depends how much u drag ur knee and what type of pavment u do it on. My friend has some and they show alot of wear n tear over the month that he had them. I modifed a knee pad to accept the real knee sliders and they have drag marks but show no real marks of wearing down. PLus the plastic is bout 1" thick so I doubt I'll wera through them any time soon. I think it uses a harder and less friction type of plastic.
nah, I made them to save ALOT of $$$. The IP2 pipe is damn cheap. It wasn't around when I did mines, but I'd be happy to spend $100 on that pipe (I though having to pay $240 for a modified polini pipe was CRAZY). It seems like a good pipe too. My buddy just got one and boy is it quiet!!!!! Think it has a better powerband then the polini 6.2 pipe. I made a pipe simular to the IP2 pipe and it blows the other pipe I made away in both top speed and acceleration. Throttle responce is better too with the fatter pipe. I'm gonna fit the polini clone pipe I made to fit on the X1 and see how that works.