I just put a Big Gun Race full exhaust system on my XR4 and changed the jetting to 60/160 needle clip in the second slot, 2 1/2 turns out on the screw, pulled the snorkel and installed the Uni. I just fired the bike up for the first time since the install and I must say that these mods made an enormous difference. The bike seems to be very strong all the way thru the throttle, and it idles perfectly. My question is when I blip the throttle there is some hesitation...maybe this is normal and just never noticed it on the stock set-up. Is there a way to minimize this or should I just accept it and live with it til I can afford a pumper carb?