I've ran/run 1 hp with both restricted gears.
1hp first gear and then 2hp second gears.
and both 2hp gears all with polini/Gila kits and derestricted and or side bleed estroil pipes .
If you run high enough gears 1hp first gear 13 tooth and 2hp second gear will catch the pipe in the band if a estroil type.
For me and my za50 bikes I like hi geared sprocket combos and low rpm pipes for long service life