Originally Posted by utopia

I don't have personal experience, but I've heard lots of reports of high power replacement headlamp bulbs melting plastic lenses.
The std unit on my monster has a glass lens but was pretty feeble, so I took the cautious approach and replaced my bulb with a Philips X-treme, which is claimed to give 80% more light (latest design claims 100% more).
While it wasn't 80% better, it was nevertheless a worthwhile improvement, and being rated at the same power its unlikely to run much hotter (if any) than the std bulb.
A quick, cheap, simple improvement with no strings attached as far as I'm aware.