I followed the instructions here and looking up my tailpipe, it looked the same as the pictures here.
If anything, I thought I felt a slight increase in power, but that was probably due to the fact that I love getting on the throttle even more now because of the awesome sound
Zero increase in drone and no annoying "coffee can muffler" ping/rattle. Excellent sound
I really noticed an increase in throttle response in the 3000-5500 rpm range. I have no regrets and even want to increase my holes from 9/16" to 3/4" or more.