NEAR THE END OF LAST SEASON I CHANGED MY NEEDLES ON MY CARBS SOMETHING A LOT OF POLARIS OWNERS DID TO GET RID OF THAT LOW END BOG BY INSTALLING RMK NEEDLES,IT HAS WORKED BUT I FIND TOP SPEED IS NOT WHAT IT WAS, CAN NEEDLES AFFECT TOP SPEED ?

They can. If the needle is causing the mixture to be lean or rich at WOT it can effect top speed. For example: if the new needle is larger in diameter at the tip and is the same length as the stock needle, at WOT the mixture will be a bit leaner. The opposite would be true with a needle that is smaller in diameter. Generally, a different needle will effect more than one throttle postion as far as the engine state of tune is concerned.