I can't comment specifically on the YZ 144 Kit, however, I did have Eric put the KX144 kit in my 2001 KX125. I asked for the MO Better Everywhere Port Job with the kit. I can say this, the 144 kit was the way to go for me. It boosted power across the entire spectrum. The bikes Mid-Range hit is nothing short of awsome. I was faced with the same choice, my plaiting on my cylinder had already came loose and I had to do something. So, I decided on the Big Bore kit. I would be very hard for me to get used to a stock 01 KX125 now that I have made these mods to my bike......I hope some of this helps:cool: