tweaking

I just installed the UFO 4-1 Dragstar exhaust, I live in Denver, CO ***a mile above sea level***. The bike is running lean at 3.5 turns. Do I need to change jets? If so what do I need to change to? On another note, I installed an RX1N gauge setup and need a little help with a few things...

I took the bike out yesterday and she runs great, a little lag in the throttle but i think it's just too much slack in the cable. My main concern is that when I was stopped at an intersection the bike died randomly. I started it back up and rode until I hit another intersection and it died...