How to extract more power from 125 Halley

[Vladko]

Hello, I've got a GG 125 Halley from 2009. It's an amazing bike and I love every bit of it, except that it's kind of slow. Are there any restrictions on it that I can remove to give it a little more grunt?
I've already removed the restriction "plate thingy" from the resonator and jetted accordingly (I overdid it and it's kind of rich now, but I'll get it sorted) and that's about it. It doesn't have a powervalve, all the openings in the cylinder where the PV assembly would sit are blocked off. By "blocked off" I mean that it looks like when the cylinder was cast, they just didn't make the openings for the PV. The rear sprocket is 39t, not sure about the front though. The carburetor is a 26mm Dellorto (can't remember the exact model right now) and the reeds are V-force 3.
The lack of PV doesn't really bother me, in my opinion the "laggy" feeling makes the bike more fun, I'm looking for some more mid/top end. I was thinking about taking the carb to a friend to bore it out to 28mm on his lathe (maybe more, haven't checked how far it can go yet), what do you think?

Thanks in advance and ride safe!