The Courtesy B-pipe is a quality, Stainless, mandrel-bent, 2.5" diameter mid-pipe. It removes the bottleneck that occurs as exhaust gases try to exit the 2.5" exit of the cat and enter the approx. 1.5" diameter OE midpipe.
It has a resonator several inches behind the cat to help reduce noise. However, the increased diameter WILL increase the decibels emanating from your exhaust - physics in action. If you have a header, as I do, your exhaust note will be even louder.
As for improved performance, it is a step in the right direction. When I added the b-pipe and muffler(Courtesy), I banged against the rev-limiter (in happy surprise) on my first hard launch. The rpm's continued to accelerate past 5K, rather than tapering off as they had with the stock section.
If you do choose to purchase the Courtesy muffler section, you may be disappointed. The section of the muffler pipe that meets the b-pipe necks down to STOCK diameter - a concession to allow the b-pipe to also mate with stock muffler sections. I recently had this section cut off and replaced with straight 2.5" diameter stainless pipe.
CB