I had the UR pipes installed by a friend where he rents the garage section of a shell gas station in Burbank, Ca. I looked when he installed it and it was very easy, just make sure to put some pressure on the pipe near the oil pan pushing it away from the oil pan then tightening the downpipe on the turbo, on my car when I made hard turns the downpipe made a thumping noise when it hit the oil pan, but when we loosened the downpipe and put the pressure and tightened it, it never hit it again.

 

Reading your post again I thought that you where insatlling the UR system , as far as the cat if it is a 2.5 inch cat then any place will do, it is a 10 minute job.