I've been meaning to comment here. There are no longer any good 3-1 exhausts manufactured....your options are limited to scoring a used one from the good old days or to make your own. I threw one together myself, and if I had access to a nicer bender it would have come out even better, but for calling in a favor to have an exhaust shop buddy make me some degreed bends to work with I'm super happy with how mine came out. I'd offer to make another, but I don't know if it clears stock foot controls as I made mine after switching to custom built rearsets....and then I don't know if I could feel right making one to sell using crush bends....
I measured the angles on the stock head pipes to make a few bends
Then I took some of the left over straight pieces and cut them up to fab a 3-1 collector (I did smooth it out a bunch with dremel bits, it came out pretty smooth in the end, this was early in the fab)
https://scontent.xx.fbcdn.net/hphotos-xpa1/v/t1.0-9/1489188_1451695525044577_1813897014_n.jpg?oh=1d028e39bc72fc4256b08b49311221c5&oe=55813DF7/img]
[img]https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-xfa1/v/t1.0-9/1601351_1451696901711106_132735105_n.jpg?oh=3fd177afd6d6fc50c297c34bbf8cb2bd&oe=558DF4CA&__gda__=1435940093_47b60aaf5b1921aefac30b47544b5612
measured a dozen times and cut the bends to make this
finished it off with a triumph style muffler I bought at a swap meet for $20
I shot some video of it on two different bikes....the one pictured wasn't running yet so I tossed it on my running bike first
https://www.youtube.com/watch?v=wdoyYPYKVeQ
if I remember correctly now that I looked at the video again, the only thing stopping it from fitting a stock xs750 is that the brake lever wouldn't engage before getting stopped by the muffler. could likely heat and bend the brake lever to clear it though.
I've thought about making another using the TCbros builders kit, but I don't know if I'd like cutting U-bends to the correct angle and have to smooth out welds that are mid-bend for a seamless look. I wish I had access to a nice mandrel bender to make one-piece headpipes
would need two kits to build one, or maybe three kits to build two would be better
http://www.tcbroschoppers.com/yamaha-xs650-builder-exhaust-kit-1-5-inch-diameter.html