I would warn against looking at a tire sidewall for pressures on ANY car, look at them an tell us is says it's probably way too high. If it wasn't so cold tonight I would check what the standard tires say.

Try a couple psi less than what you have in now, then a couple more - see what seem best, and like you have done see if anyone has experience of those sizes on the Crossfire. My guess is a little less will feel better, it shouldn't be very different to the stock, the hieghts and profiles aren't a million miles apart.

Some more info might help - whats the temperature / climate like, what sort of roads were you driving your bobsleigh on?