Relative volume is not as useful as I imagined it would be. I used it for a long time but rarely found it helpful. If a stock is up +10% and the turnover is above say $1mill, then it's in play, regardless of the relvol.
The best level 2 visualizations are on Iguana Spark, but I don't think they have a scanner for pre-open. Agree with what handy said.
TV has a scanner for intraday moves if that's any help. And relvol indicator.
