Pretty much for looks only - didn't want the drone of axlebacks. Little bit lower growl possibly due to the megaphone affect of stepping to 2.5" output, but nothing much if at all:

Exhaust Tips:
http://www.summitracing.com/parts/imm-577555/overview/
Adapters:
http://www.summitracing.com/parts/wlk-41958

Side Note:
I have had the large intake resonator on and off a few times with a precise plug (see my post) and think it actually loses a bit of power with it off. Don't ask me for an explanation, just my experience.

Enjoy