I backed mine up on ramps and it was more than enough room under the rear bumper part. Under the middle, where the pipes separate after the cats, was a bit more cramped, but nothing so bad I couldn’t work.
The bolts to cut (I believe) are just for holding on the heat shield under the body, so it won’t affect the stock pipes at all. The part you cut is the excess part of the bolt anyway, so if you ever need to remove the heat shield it should still be possible. It was quick and easy to do with a Dremel.
Let me know if you have any other questions.