Gotta put my 2 cents in. I had both my yz125x and yz250x heads modified by RK TEK
I put the 125’s on and went for a ride. Little while later I went out on a longer ride.
Definitely a big loss of power everywhere.
Now I know why all the so called enduro riders like all these heads....
The second is to never get rid of that problem ?
In that the case, I lie all the time ?
I would pass by popping a long ass Willie though ??