Stage

Actually, shallow staging to deep staging will make am obvious difference in RT and ET. (I forgot the "rough" numbers, but even that will vary between vehicles, suspension set-up, converter, gear, bias-vs-radial slick, front tire size, etc.) A car can roll quite a bit and still keep both prestaged and staged light on.

Remember that the beams are a certain amount ABOVE the track. So tire diameter affects it as well as air pressure. Less air "flattens" the front tire and brings a wider portion of the tire down into the beams.

Here is some information that can hopefully help one understand more of the basics and variables.

The Staging Light -- Drag Racing