Did not fit out of the box - modifications required.
I have a 1/2 ton 1999 GMC Sierra Extended Cab Long Bed pickup and Gibson is about the only company that still makes an aftermarket cat-back system that will fit my truck. It was supposed to be a simple bolt-on installation, but the exhaust system was too long and didn't line up with the stock exhaust hangers on my truck so I had to cut one pipe shorter. I'm still working with Gibson on a few issues, but overall the quality isn't bad however the fitment issues were a huge disappointment.
Corsa Performance Exhaust (or rumbling down the road)
I had a Corsa exhaust on my 2005 GMC Sierra when it was an option from GM. The new system on my 2015 seems to be of the same good quality and looks. The sound is more of a throaty rumble that quiets right down on the highway with no drone coming in the cabin. I had a professional install it in about 1.5 hours. Overall happy so far.