The RX-8 pulls 250 hp at 8500 rpm.. and it's 30% lighter than the 3rd gen RX-7. It's REALLY fast.
There are a few other differences between the Renesis and the Wankel:
1) The intake ports and the exhaust ports are both in the side housings, unlike the Wankel, which has peripheral intake ports. This means, basically, that there is no overlap. So, longer powerstroke and better heat efficiency (also better fuel economy, what do you know).
2) The intake ports open sooner, and the exhaust ports open later = longer powerstroke.
3) The Renesis is not as tall as the Wankel, which allows it to be placed 60mm closer to the center of the car than the RX-7. Hence, the 50/50 ratio mentioned in a previous post.
Remember that you are paying for R&D right now.
So go out and buy those 8's... I read that if they go well, Mazda will be developing a new RX-7 for 2006.