OK, I'll explain what I did but in no way encouraging people to over drive HID lamps, they may explode, that's my disclaimer :)
The Mozo ultralight, I did it with 55W 4300K ebay bulb + 75w ballast,
most beautiful tint & perfect beam on HID I've seen. run time too short, sold it.
I got another one that I tested with stock bulb with 55W ballast, works fine.
But I am keeping the light as is for now, to use as reference light.
I tried two sets of ebay 4300K bulbs, 35W & 55W. could not get the tint or beam profile back to what I had in the 1st light. I am a white wall hunter, a HID light to project a perfect beam with SMO reflector as my 1st Mozo was rare to see.
The Mozo 6" Mega I used Philips 35W 4200K bulb. Drive it to 75W (My estimation is 65W at lamp).
The Philips 4200K bulb gave a huge gain in lux, about 40% gain even at 35W form,
but it gave a hint of ugly pee green tint, again I am white wall hunter & picky about tints.
I didn't like the tint. Philips bulb is D2S or something like that, you'll need to get pigtail conversion too.
FYI, 55W & 75W ballasts are rated at in put (cheating), 35W ballasts are rated at out put.
So 55W ballast out put is 45W or so.
I went a little crazy there with 75W ballast/35W phillips bulb, not recommend that combo.
I took some risks on slight over drive as smaller watt bulbs has shorter arc.