Why would you want to? They are FOG Lights. Installing the wrong bulbs is
probably going to reduce their usefulness for the intended application. If
you are one of those inconsiderate people who rides around with fog lights
on all the time, then making them brighter will only annoy more people. Is
it your goal to piss off your fellow drivers? If you need more light for
driving on mostly empty / dark roads at night, then buy a good set of
driving lights and wire them to come on with the high beams. Don't give in
to the temptation to compete with rice boys.

Ed

If it's just a bulb... be careful about changing to brighter (higher
wattage) bulbs. I have seen many instances where after this was done...
problems from the additional heat and current draw... including melting
of various lamp housings and bulb sockets will cause failures in a very
short time.

www.telstar-electronics.com

Question: Do you want brighter fog lights or do you want driving
lights?