I recently put in a 80mm big bore kit in my 250x. Still running stock cam, fmf megamax II exhaust. I bought a newer model 300ex carb which is 32mm compared to the 29mm stock 250x. i have a 40 slow jet and a 140 main. it runs well, but i have a 400ex carb and i am wondering if it would be a noticeable difference if i put the 400 carb on, properly jetted of course. if it's not going to make a good difference, i'll just save it for my stroker engine i am working on.