Hi all! I recently purchased a MBRP catback for my focus and am considering installing it myself. On my previous car (which wasn't a focus) I had an exhaust shop install a catback for me. I watched him install it and I noticed he smeared this thick black stuff around the bolts before putting them in and tightening them. What is this stuff and would I need it ? It was in a small green canister if I remember correctly. At the time I didn't think anything of it but I got thinking about it and now I'm worried I will need this. He also smeared it in and around the hangers. I got thinking about locktite but he wouldn't use that stuff around the hangers. It must have been some thick lubricant any ideas ??