e50

e50 misfire/trans slip

instead of shifting at 6k rpm to hold more boost , i tried shifting at 6500 rpm so it can help me get to 130mph in 5th gear without having to shift into 6th gear but now its throwing the same combustion misfire codes if i don’t shift before 6k rpm. How can i get to 130mph without having to shift into 6th and without getting a misfire after extending shift to 6500rpm just to get to 130mph