When you could run with no helmet I shifted by sound.With it and my hearing going I use the light.Too many years of air tools and shooting big guns I guess.I can rev past 6700 and mine is still pulling strong.I just figure that 6700 is good enough.Ill find out more when I get the Dana cut down and 4.30s instead of the 3.91s that are in it.4th gear it drops RPMs a lot with them.Rocky