I just finished reading a similar post. I am putting a 4 into one Yoshi Pipe on my bike. Will there be any ill effects if I put on the pipe without a Power Commander for the time being. I hope to have one next week, I just want to get the exhaust on now and take it for a ride. Will it run lean and hurt anything running it this way or will I be OK to ride it for a bit with just the pipe?