Won't a 21mm dellorto give me more mph than a 14mm bing? I have no idea about the carb signal... The more weight you shave off the shoe, the later it will engage, right? So with those tight ass springs, I'm not going to be taking off much weight if I want it to engage at 4.5k. I like the link you sent me, I'm getting it just HERE. And isn't there some spring tuning involved? I need to figure all this stuff out. I can't really come out to you, I don't have a ride. If my ped was working, I totally would just hop on it and ride to Worchester. You can come to Concord or Carlisle and take a look at the pipe. I have a Maxi, like you and it's on it right now. Not to much work, just bend out the pedal a bit and add spacers.