This was posted in the cockpit forum but I thought I'd also post it here since it deals with your area..
In my quest to find a harness bar for my car for autocrossing this coming year I came across the company Stable Energies. My coworker has one of the ars installed in his 944 so I contacted them to see if they made on for the WRX. Currently they do not have one available but are interested in designing one for the WRX. They are located in Garfield, New Jersey and need a car to measure and test fit for a new design. If anyone is interested their website is http://www.stable-energies.com/. Send them an email if you're interested. All of their other bars sell for around $100 so it would be a nice alternative to the pricey speedware bar. Let us know if you have any luck.