I was browsing on the GS board and they have a 5 watt parking light in their high beam, and they said most of them use a PIAA 18 watt bulb and that matches the HIDS.
18 watts in a 5 watt assembly? Seems like taking a chance.

 

Those 5w bulbs are DRLs. They are fitted inside the high beam assembly which is usually the most heavy duty/durable one on the car. The issue with our parking lights is that a higher wattage bulb melts the plastic dome around it. That plastic dome is removable though, except only inwards, which means you'd have to open up the headlight assembly to extract it. PITA, but it'd probably do the trick.