I bought a DMC Afterburner full exhaust for my bike. I had bought the FMF Power Up jet kit along with it, but come to find out when it arrives that it doesnt have large enough main jets. The largest main jet that it came with was a 148, and i needed a 160 and a 155. I installed it anyways, seeming as I had just put this new pipe on and was just itching to start it up to hear it. I fired it up and sure enough, probably 30 seconds after i had started it the headers were glowing cherry red. That was just from warming it up. I wanted to take it around the yard anyways to try it out, figured it couldn't hurt it too bad, so I took it out of my garage and rode it around the driveway and up the road a couple hundred feet. Keep in mind that we were right in the middle of a cold snap, and it was 20 below zero outside. I looked down at my headers and they were glowing bright orange after just putt putting around. Running really lean. It had no power to speak of. I ran it with the choke all the way on from where I was back into the garage and shut it off. I ordered the right sized main jets right off when I got inside. Got them a few days later and put them in. The bike ran good after that, i mean the power I got from the pipe was incredible, but now, if I let it idle after it was warmed up, the headers would glow bright orange like before. It was bad. So I ordered 27.5 pilot jets. They were too big. It would fire right up, but once it warmed up, it would stall and would smell bad. Flooded. 25 pilot jets are what i put in and they are just about perfect, but they are a touch on the lean side. When the motor is warm, it idles not quite as steady as I would like, but if i bump the choke on a bit, it idles like a champ. IDK if any of my rambling will help you or not, but this is how everything played out for me. Runs good for the most part.