I know when there was a gentleman's agreement between manufacturers, Kawasaki on their then new ZXR750 made the inside of the carb tops restricted in the same way as above only I think they were rubber and could be cut back but you could make it a full power model by fitting carb tops from the then undisputed king of the roads the ZZR1100.

 

Had the carbs back from the sonic cleaners, removed the stainless restrictors from the inlet manifolds, replaced the jets with the correct 122, replaced the air filter (the one fitted had one end gaffer-taped up). The mixture screw was 2 1/4 turns out so left that for now, the Haynes manual says UK 3 turns out, any experience / thoughts.
Refitted to bike and before I changed the exhaust I thought a little test ride might be a good idea. With the mixture not right it was a little lumpy but what a difference, pulling strongly to the red line and noticeably more mid range grunt.
Like having a new bike again, just need to play with the mixture screws and balance the carbs and burn some rubber

 

You've probably added another 30 ponies

 

No way should you have any plates inside the inlets. Jets are obviously ALSO to restrict it for JDM. I'd be amazed if it had different cams. Is it running properly now? .

 

It's going noticeably better, mixture is near enough, with no flat spots pulling strongly to the redline in 5th & mpg is not that different from the restricted version. A good result for 4 new jets

 

Probably the cheapest ponies you'll ever buy! Enjoy them