ballast and bulb queries

[URfinest60oz]

i have a 600 watt ballast, was just wondering if i could put at 250w hps bulb where my 600w belongs and it being cheaper on electricity. as it would be still going through my 600w ballast.

as im growing in a cupboard would change bulbs effect yield?

:(

plz help

[killerweed420]

I've seen people do it but it burns your bulbs out a lot faster.