I removed the exhaust restrictor & the thing is still very slugish. So against the the advise of many I pulled the intake off to remove the restrictor there. Well that intake is small. You can't just pry the plate out so I drilled it out with a 1/2" drill bit. Let me tell you this thing screams now. It's way too fast. I'm making new restrictor plates to put back. I'm making them like the exhaust plate. I think I should have stopped with a 1/4" bit. If you open yours up be careful. The new 50's with suspension can probably handle the speed better but the hard frame 50's can't.
You were right about the manifold that is permanently attached to the carb. A Suzuki tech put the carb on a bench and bored the manifold for me. There is such a huge difference in power with the Graydon Proline pipe and carb work that I've had to use the throttle limiter for my 6 year old.
The restrictor is in the intake manifold between the carb and the cylinder. You can take off the intake without removing the carb. I say its too fast because there is no suspension, but it definately helps to get it moving. No more pushing to take off on the slightest hill.