Light help needed

I have a garden going in the crawlspace in my basement, in the middle of the garden is an iced widow and critical sensi star plant. I have one of the dimmable Apollo 600w HPS ballast running a 400w MH bulb at 300w (50%). Can I turn the ballast up to 75% which is 450w and not blow anything up? If it shortens the life that would be fine, I'm ordering 600w MH/HPS bulbs next week so I don't really care about reducing the life, just don't want anything to blow up or catch fire.

Thanks

Don't turn it higher than the lamp supports - I would advise just to keep the light at 50% and play around once the 600W has arrived.

Thanks for the reply. Yeah I might just keep it at 50%.