430watt hps bulbs on a 400 watt ballast....

[Shovelhandle]

I know a guy that runs 400w bulbs in his 1000w ballast.lol Swears by them.

Yes? And I know a place that called me after they kept blowing 400 watt lamps in their yard lights. Come to find out that they were 1000 watt fixtures. I'd say that it isn't worth trying a 400 in a 1000. Check on the 430 watt lamp manufacturer about specs for running that lump in a 400W fixture.