I usually visit some friends in Colorado. I came before with my FC but it was NA back then. Now its turbo'd. The question is, should I still go with the 3 inch down pipe or go 2.5? I ask this because when I came with my NA it felt really weak running on my RB headers with my cat back. Thanks!

 

That wouldn't help. You loose power when the air density is lower, there's not much you can do about it.

 

Yeah thats why I might just switch the down pipe to a 2.5 when I come see my buddies there. Then switch it to the 3 inch when I get back.