I have a 155 boost 3" luv the thing. Now the 3" does trench more than the 2.75 but on the boost it's worth it to me for the Xtra hook up of the 3". The 2.75 works better on a N/A then on a boost it lays over to easy. I ride dubois mostly and after a couple hundred miles the 3" breaks in a little and don't trench near as much. I have a 165 9r khaos 2.75 and a 155 pro 2.75 if your going 165 I would definitely go khaos. My .02