I have a dirtbike, Transworld motorcross, or motcross action somewhere that tested them on a 2 stroke. Supposed to make throttle response quicker, run smoother, and you can run leaner. The write up was very positive.
I put a v-force in an am pleased. I think the Power Nows are close to $100. I got my v-force for 129 delievered and love it. Makes a HUGE difference in the way the KX hits.
I think I have seen the same thing as the PN's in dennis kirk for around $30.
I know a v-force makes a huge difference, I have heard that a spacer makes a big difference as well, as far as the PN goes- Try one and let us know!!! I will try and find the magazine and let you know the issue.
Good Luck,
Jay