I drilled 4 x 25mm holes into my lid. Jetting was factory, only cans and wire splice done. It definatly gained top end but made the slight flat spot it had mid range worse. I taped up 2 holes and it felt much better mid range, and still just as good up top.

I notice a very distinct differnce in induction noise from going from 4 to 2 holes. 4 was very raspy. Simular sound to open carbs. Bit annoying on light throtle, but tough as on full gas. With only 2 holes, all that went away and it was just left with a nice growl through the rev range and the nasty 2-stroke flutter at light throtle was gone
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