AS far as I am concerned, the OEM is a very good CDI, you can't really beat it, I have two bikes with Dyna FS, but the only reason I have that is because of the 3 plugheads where the timing curves MUST be altered..........I would just keep it as a spair. I ended up with one. I run an oem cdi on my raptor. I put the pro com on my bro's. The only reson why was to disable the reverse rev limiter. He keeps the oem one on hand as a backup. Aftermarket CDI's other than the Dyna have had reliability issues.