Fit & finish are excellent, feels super high quality and they make a tuning fork noise when you hit them right. Not sure of power gains, I got these mostly to prevent my clutch bell from eating it's circlip. It's quick thooo I would strongly recommend getting the bell bored out for a needle bearing in high stall applications, I seized two bushings to the crank before sending the bell off to the machine shop.
Edit: the clutch gear walked out of the bell about 1/8th or so inch after about 100 miles or so with a KTM clutch, causing the bell to drag on the clutch. Caught it in time before it walked out all the way so nothing was damaged and hopefully repairable.