Yeah I dunno what the deal is with the tecno hunter, I've seen some bikes rip with it but it defies all logic. I keep a boss/biturbo around for gut checking builds, that would maybe be my next step if you really think it's leaving something on the table.
Like others have said, without porting you're really not gonna go much faster if 38 is your real flat ground gps speed. Most tomos lovers lie like crazy about their top speed.
Also what jbot said, you'll get a higher top speed with lower compression and more advanced timing. You'll get more torque with more compression.
Seriously though, I'd get out the dremel and open up that exhaust port, it's stupid not to, I don't even know how fast a stock a35 is supposed to go since I always port them first thing.