GS oem exhaust, like so many others, has internal weld bead where header pipes butt up against flange, on cylinder side. Presume they weld inside so outside is prettier. Bad idea.

On other vehicles, people grind these out, making inside smooth.

1-Worth doing on GS?

2-Would it require rejetting?

I would normally never bother but have pipes off and it looks pretty bad in there.

I don't think it makes a damn. A tiny bead isn't going to change your backpressures, I wouldn't even bother with it dude.

you are almost certainly right and I already agree but had to ask.

The bubbly bead is occluded by exhaust port. Port edge about 4 mm upstream. So, can't make a difference if I cut the bead away. 

Miata, and Katana, they cut it and grind it, with pride. Miata, re-weld outside each header pipe.

Katana requires rejetting. Miata is EFI so no rejetting within x% more flow.

Its sloppy manufacturing.

JR

People say the same with my honda xr250. I saw it when i wrapped my pipes. Never did it though. Although i heard it does make a good difference with a few other minor mods here and there...that is with the xr250 which may be easier to make faster as it is a smaller motor..?? But seems like more work and a hassle to deal with that its worth.