Apply your colored bulb covers to all of your gauge bulbs.  The pyrometer and trans temp gauges use (2) T-5 size bulbs each.  The boost gauge uses (1) size T-10 (shown here).  If you find that your boost gauge is slightly brighter you can mark the bulb with a permanent colored marker as shown above.  Just a few lines will do.  Make sure you cover the area that the bulb cover doesn't cover.  This is where white light can be emitted.