BigJimmyW13
XS650 Guru
1/8 is plenty if you do it as inxs laid out in his diagram C, 5/16 is serious overkill. Go with 3/16 if you think it needs to be heavier. You want the gussets welded as far to the outside of the tubes as you can without causing tank clearance problems.
Brother, I'm not going to give every dude I come across a hard time about using that tank. It's cookie cutter. It's also YOUR scoot. If you look at my comments, I don't usually go off on a guy's personal build. It's the "professional" builders who use these tanks, unmodified, along with other bolt-on and prefabricated crap that I get tired of. I can think of a few on this site. I've been trying to ignore them. We'll see how long I can hold out...
On the neck gussets. I had to cut them out for rerake. then ground them down in more of a C shape.
I don't think Teebs gave me shit about my tank b/c I at least modified it to have a fuel gauge..