I recently got 15.491, my 60 time is crapy at 2.8 runninn at 88.89 MPH with just cai/ex and i get headers this week so i hope it will make a difference. And yes your right about Colorado, the air is very crappy. im not going to lie the first time i ran i could not break 15's but not to brag, but i pull 15's all the time but im working on 14's and i know its possiable.