Hi @dom14.
Can't remember the wattage. May have been the one you quoted, but low beam was atrocious, so was probably xxx/55.
On the 6000k "brightness" - lumens are your measure, not Kelvin. K is the theoretical colour of light produced by a matt black (insert substance that I've forgotten here) at that temp. More a measure of colour than brightness.
FWIW - I've changed our non-patrol back from the Philips 5000Ks i put in as they were actually worse for brightness than the Narva Plus120s in there now, which are much further down the colour-temp scale, but must be higher lumens. I have the benefit of H4s - not sure what's available with sealed beams.