What exactly is a TOSS when talking about singles. Never ever heard it applied to a single before.
As for Vr (a term that's not usually used for a lighty) I'm guessing we are talking about raising the nose wheel, why would you increase this speed ever (unless you're over gross)? The aircraft's performance is based around IAS, so while TAS (ground speed in this case) may by greater with higher DA's there's no need at all to be playing around with the speed at which you raise the nose.
For a given weight the aircraft's stall speed remains the same no matter what density altitude therefore your minimum 50 foot speeds are also always the same. The best rate of climb speeds will change due to changes in power output (assuming normally aspirated), however the change will generally be small, about 1 knot decrease per 1000' DA increase.
I have to ask the original poster why he/she thought it a good idea to increase the lift off speed? If your instructor suggested it then he/she needs some remedial P of F.
Last edited by 27/09; 26th Jan 2012 at 01:18.