"Where did you get the plates ? I can't find any and don't have access to a machine shop to make a set."
I bought some CF plate and cut my own using a jig saw (tungsten carbide blade), drill press, and some rotary sanding tools. CF is very abrasive and I think it ruined the drill bit. I made two sets and listed the second for sale but there were no takers. Maybe no one noticed. I was going to list it on the WERA forum but never got around to it. Fits K1-K8 1000 and some earlier 600/750's as I recall. But nothing as late as yours.
"If I leave it alone won't I get pop[p]ing when I change the exhaust system?"
I think you will. You also need to block it off if you're doing dyno runs and measuring the AFR via the exhaust gas.