In the 5th gen prelude, when you remove the instrument cluster, there are 4 twist bulbs in the back that light up the speedometer, fuel, temp, and tach. these four must be converted over to LED. I reccomend an 8mm bulb because anything smaller will not produce enough light to light up the cluster, since it is only 4 bulbs total. Of course you also have access to the other bulbs such as the Airbag, SRS, ATTS (if SH), etc. All of these bulbs have filters and are very difficult to remove, I do not recommend doing this. Also, another word of advice, do not remove any of the needles. There are no filters behind the gauges. Simply changing those 4 bulbs will illuminate the gauges nicely, although you will have to play with the direction of the bulb to get the best light through the cluster.