Seeburg -

I actually did do this once when I decided that after I had leveled off at my final cruising altitude that I would being flying much faster than what was on my flight plan. I swear I thought I could hear the initial confusion when I reported my change in TAS to him and then something akin to annoyance that I had taken the air time to report such a trivial matter. Needless to say that I didn't worry about it too much since (right or wrong). I certainly got the feeling that ATC didn't really give a hoot.

USMCFLYR