TT vs XT350
The primary gearing is different between the TT and the XT, the oilpump has a nylon gear on the XT, metal on the TT. The airbox flows much better on the TT. I believe the intake valves and perhaps also the cam is different. And I thought the carb is slightly larger on the TT. All that gives you about 3 HP more on the TT.
The trick with the carbs is to get the 2 carbs more balanced. On the TT the stock jetting is 122 primary/125 secondary. I run 118/120 on my TT. I also run a ported head and a K&N filter. I did go back to the stock exhaust many years ago beacause of noise, and also found out that the bike was actually easier to ride on singletrack in the woods. The powerband is much smoother and broader, and it's in stealth mode.
Do it in the Dirt!
1974 DT250, 1980 TT500, 1986 TT350, 1993 KLX650C, 03 KTM450EXC