With the Ackerman plate, which hole gives more ackerman effect?
Looking at the buggy from overhead, is it the most inside hole?

The rearward holes (closest to the back of the car) will quicken your initial steering response.

I agree with that too. I use the rear holes.

thanks for your help guys

forward hole= smoothns out steering response-car reacts smoothly-better suited for smooth flowing tracks or high speed turns
rear hole= • Quickens initial steering response• Car reacts faster to steering input• Better suited to small, tight tracks
On the sp2 I have 3 holes and run the middle, if its a tight track then I'll move it back towards the car.
Remember, when you move or change one thing, it will effect other things, like camber and or caster angles.

You should print out some set up sheets. I mark up a set up sheet for each different track I run on. That way I can set my buggy up the day before I race and make any fine adjustments day of the race. Your ackerman plate is only one of many adjustments you should make from track to track.