I don't know that EG does or does not modify carbs. If he does, it's new to me, though.
..a lot of things are (new to me I mean).
The carb mod for the the 200/220 from RB-Designs is the same. The KDX OEM carbs are not the same (different sizes, different jetting), but the modification is.
No, Ron's mod is not the same as a PowerNow thing. His divider is on the downstream side..where it does something. The upstream divider purpose has always eluded me..I don't know what it's supposed to do 'up' there. Nothing, most likely!
Ron's mod has been dyno-developed and tested for years. It's been tuned by numerous riders in different conditions for years. It works.
Does the 200 come with this (the RB mod?) stock? No. The 200 'H' carby is a Keihin PWK small body 35mm carb. The 220 'H' carby is a Keihin PWK small body 33mm carb. Other than bore size and jetting, they are the 'same'. Same type of jets, same slide, same throttle attachment, same bowl, float etc etc.
Yours has one what? A divider? Upstream or down (airbox or reed side)?
M0rie is correct. Mr. Black marks slides that he machines. The OEM slide has a 5mm cut-a-way. He cuts them to 7mm. There will be a 'G' stamped on the top of the slide..where the needle retainer nut screws in.
'G' as in the
7th letter of the alphabet...as in
7mm?
NEAT! 'eh?
If you already have an RB modified carb...you're already setup with the best carb setup (pending your jetting) you can get. You don't want to know how bad an OEM 33mm carb is/was.