Haha, what a coincidence. I'm also finding a high-poly Pyro-GX as well, to turn into a Transcendence player ship.
At the moment, I'm making do with a 3DS model I found
on the Descent Network's file system, which is miraculously still working despite the website being more or less dead, with all links to these files broken. If you're using Blender, the 3DS executable works perfectly. I converted it to OBJ using Blender before importing it into Maya.
I'd like to use MetalBeast's Pyro-GX, Bubbalou's Pyro-GX or the Into Cerberon Pyro-GX if I can, but for now, I'm using the Pyro-GX I found in the link above. Textures are rubbish, so I'll attempt to do some UV mapping on it over the next fortnight if I have the time.