There is a shop here in Lansing called Clutch Dynamics that may be able to help you out. I know that they can get pressure plates that are approx 10% increase in clamping load over stock, but you may want to give them a call to find out more details. I will PM you with their contact info.

On a side note, I will be posting this company's contact info in the near future for anyone who wants a clutch. They are far more reasonable than any aftermarket clutch and their quality is outstanding. I speak from personal experience, and soon you will be able to ask XtremeRS and Jason_ESiT what they think as well.