xenons on my gti

I've had a random thought which to me seems reasonable, to you guys who know what they're on about, seems stupid (maybe) .

Anyway, I've got a gti mk5, and I'm a fan on bright headlights. now I've always believed the xenon headlight units are sealed, but the units have 2 other bulbs in them, Is this saying they're not sealed and i can replace an individual bulb?

The dipped bulbs look crap while the xenons are gleaming away, and i wanted to know if it is possible to change the sidelight/dipped bulbs for more powerfull ones which light up alot more than what they currently do?

If thats the case can i get a bulb which is brighter than whats on there and have one which gets brighter when i put the main beams on.

all I'm after is 2 bright bulbs instead of one crappy dipped and a main beam one.

hoping that makes sense,

cheers