I have been searching endlessly for days. I recently acquired a large collection of what say 320Watt Pulse start Metal Halide Fixtures. So like anyone else with a tool kit and curiosity would do, i open it. I was surprised to what I found inside. It had a multi-tap transformer, a capacitor, and an IGNITER. Funny I thought to myself, I thought only HPS used igniters. So I turned to my friend google and looked up some schematics of HPS wiring diagrams. I find that it is EXACTLY how this metal halide fixture is wired. So I plug in a 320 watt metal halide bulb and flip the switch. Works great. Now I go outside and with an extension cord(LONG) and a GFI outlet try it with a 400W HPS bulb. Now because the Ballest was only good for 320W it was abit dimmer than usual but IT WORKED. Does anyone that knows what they are doing have any knowledge that says I SHOULDNT do this. I am going to let it run for a couple days outside by it self as a test, but just wondering what you guys think.