shiftin Q

hey, im goin to the track with my 5.0 on sunday to see what times i run, my 5.0 is bone stock and i was just wondering when is the best time to shift when racing em, i know your supposed to shift at redline to get the most out of your gears but when i do this it seems like it takes too long and i should shift at the yellow line. so my question is when should i shift when racing? thanks