How's it going everyone.

I want to run the HPS bulb at a lower wattage, so it doesn't heat up all the way and stay orange. Will it stay on or just cycle? Could this damage the ballast?

If you underrun a HPS lamp using a lower wattage ballast, the ballast may overheat.

It will overheat the ballast and it will damage the bulb as well and the bulb will be very dim.

Got it, I'll just match the wattage.

Thank you I appreciate the support.

It also depends on what kind of lamps are you talking about - American or European. For European lamps / ballasts I think that while the lamp voltage drop of an underdriven lamp will be slightly lower, the problem is not as critical as burning up the ballast. I would check the choke temperature with an IR thermometer, there is a lot of robustness. If in doubt, I would run the lamp on two 150W chokes in series. That way you absolutely could not burn anything, even if you just put a jumper instead of the lamp   By the way running a HID lamp underpowered may shorten the life of the lamp because the electrodes getting too cold. 1/2 of the power is probably still OK.

Interesting to note that my all time favorite carnival ride, German 'High Energy' by Zierer, now very sadly out of service, used large floodlights with dimmed color MH lamps, as an additional coolness for me
Lamps were dimmed in random cycles for multi-color effects. It is very hard to tell the dimming ratio by the eye, very roughly I can tell 1/3 to full power. One of the their lamps was orange, might be a plain HPS.