No issues here. Before installing mine, I was skeptical and did a lot of searching and found that the reasons against installing pulleys are based on theory. Aside from an issue with a cheap pulley welding itself to the block, (which won't happen with the NST or stillen) i couldnt find one person with a motor issue that was caused by an aftermarket crank pulley. I know several people who have had pulley kits on their Zs for years with track duty and no issues. Go for it
