I copied this from an ad on e-bay that was for a diode and some wires. The diode would light up when the Honda computer engaged the higher RPM cam lobe. Notable parts have been highlighted...
"The VTEC LIGHT is a GREAT cosmetic and performance modification. The VTEC LIGHT has been known to drop up to a FULL SECOND off quarter mile times!!! Great interior modification that is very new and rare in the import scene! High intensity leds light up at VTEC engagement! Excellent for the race track OR street usage! A plate included in the kit says VTEC BOOST and lights up when VTEC is engaged! YOU CHOOSE FONT TYPE for in dash plate AND COLOR OF HIGH INTENSITY LEDS! The VTEC light will tell the driver when the engine is in the best power band for the car to perform at its HIGHEST OUTPUT, ! THIS LIGHT WILL HELP CUT TIME OFF AT THE RACE TRACK! WITHOUT A VTEC LIGHT YOUR (sic) LOSING VALUABLE HORSEPOWER

"The VTEC LIGHT is a GREAT cosmetic and performance modification. The VTEC LIGHT has been known to drop up to a FULL SECOND off quarter mile times!!! Great interior modification that is very new and rare in the import scene! High intensity leds light up at VTEC engagement! Excellent for the race track OR street usage! A plate included in the kit says VTEC BOOST and lights up when VTEC is engaged! YOU CHOOSE FONT TYPE for in dash plate AND COLOR OF HIGH INTENSITY LEDS! The VTEC light will tell the driver when the engine is in the best power band for the car to perform at its HIGHEST OUTPUT, ! THIS LIGHT WILL HELP CUT TIME OFF AT THE RACE TRACK! WITHOUT A VTEC LIGHT YOUR (sic) LOSING VALUABLE HORSEPOWER

