Hey - here's an idea. Let's start off with a list of stuff we all may have had personal experience that we KNOW don't work. We can describe the part and the experience we've had and hopefully save others from the folly of purchasing and installing something that is basically nothing but pain and heartache. I'll kick it off: The early Edlebrock Qwicksilver carb. What an unusable piece of nonsense! I installed one on a FLT. I bought the carb from a buddy of mine because he said he "could never get it right" - uh-huh. I fiddled with that red knob on top and counted "clicks" (that's what you're supposed to to) 'til the cows came home and could never dial that thing in. I must've spent months and it still was cold-starting and stumbly. One day when it was hot, I left the gas on and went to start the bike. A stream of gas shot out of the carb like a garden hose. The next day I bought a used Harley CV carb for $60 on eBay, slapped it on and haven't had a problem since. I can only imagine if I had that much trouble tuning that thing on a STOCK bike how much fun it would be on a modified motor. I hear they've changed them since the earlier models - but there are probably some of those still floating around, so beware!