use the search function for the long form but get:
One (x1) M10x1.5 socket cap screw (i forget the exact length just make sure it doesnt stick out inside the cylinder)
I used JB Weld and a socket cap and let it set overnight. Perfecto.
you can either remove the decomp plug, shorten your starter cable, and be good to go
or of youre in a rush, just zip tie the decomp clip closed and tighten your starter cable at the grip if you can. janky but it'll work
Keep in mind, when you do this compression will look for another path of least resistance so you'll find out pretty quickly if you need seals and gaskets or not.
but def take apart that exhaust while your waiting for the JB Weld to set
ive had decent luck with letting Gunk Gel soak in it for awhile then blast it out at the local diy auto wash. Although sometimes a BBQ followed by a can of high temp paint is the most thorough and clean looking way to go