The bike is a 1981 Special II, and the exhaust is from MAC (I don't believe it is produced any longer). This exhaust was installed on the bike when I bought it, so it got refurbished when I put Trusty Rusty back on the road. The seat was reupholstered by me, not a great job, but good enough - the link to my start at seat work is here:Hi! You seems to have a 2 into 1 exhaust system; where did you get it from? You also have a nice seat! What year is the bike?
https://www.xs400.com/threads/81-xs400h-–-putting-the-trusty-back-into-rusty.20444/post-187627