So I've heard these driveshafts are not good. I've heard that if you want it dyno'd that they wont even touch them if they still have the stock driveshaft. Is this true for them all? I can't seem to find any straight forward answers. I've seen "nah you'll be fine" or "Only if you go over 100 and make more power". So my questions are, is this true? Was it all lengths and styles? If so, where are some good places to get one at? Are any parts store ones okay or does it have to be custom made?