I have a few comments.
First off, check for air leaks around your intake shim. 94 sounds way too high for only a 15mm upgrade on 50cc.
The intake is really tiny. I Don't quite remember, but I think that it was maybe 11mm on mine. It was roughly the same size as the original carb that was 10mm anyway. An upgrade in a carb needs to have an upgrade to the intake to get a performance gain. My guess is that you're just running really lean and thats where you got the extra rpms from.
When you upgrade the intake, the reeds can only handle a 12mm carb, those need to be upgraded too.
The porting is really conservative. It might help to open the ports up a little if you're confident.
The header on those bikes is tiny and long. IMO, you're going to need to replace the whole thing to get much performance difference.
They're really nice bikes if you're creative and open minded as to what can fit. I have a 19mm intake and carb for mine. I'm still looking for a reed setup. I might just end up machining one when I have time.
Post some pics up!