That looks like what's called an Ascot exhaust. Like most aftermarket exhausts, the headpipes are only single wall. That means they tend to turn blue, but usually only for the first 6" or so coming out of the head. The way yours is blued all the way down the front to the bottom bend indicates the bike was run too lean for a while. The way it mounts in the head may be correct for an Ascot.
https://www.mikesxs.net/ascot-street-tracker-exhaust-1974-79-xs650-standard.html
https://www.mikesxs.net/ascot-street-tracker-exhaust-1974-79-xs650-standard.html