I have a 07 450x that i converted to street and got it plated. I tossed the emissions crap, added a power now, cut the air box, cut out my stock baffle and chanced my main jet to a 168 my pilot to a 48 and just dropped in the 05 450r needle with the clip on the 3rd from the top. I have my fuel screw about 2 turns out. When on the highway at about 6500rpm I am getting a slight hesistation and popping from the exhaust. The bike is only a month old. My opinion is that because the exhaust has no restriction it is leaning the carb out causing the popping. The mechanice at the local shop said it was the needle. I changed the needle last night and the problem is still there. I was thinking if I should drop the clip down another notch?I have ordered an FMF powere core exhaust. I am pretty clueless when it comes to jetting so any help will be apperciated.