Thanks for the replies guys.. Im running an ultegra compact with a 9 speed cassette. It has not been cold set and is 126. Not sure if this is worth mentioning...the cassette is on a set of mavics. IIRC I needed to put a spacer on before i mounted the cassette to take up the play.
Related question. If a 10 spped cassette has a shorter stack, it seems that it could be moved closer to spokes to avoid chain rub??? will i need a spacer as well?