I have a windura500, that came with a three blade wind grabber. My top speed on most days is about 12 mph (avg). I also have a five blade turbo Torque which gets going faster but seems like the same amount of charge in the end. I have heard on the forum that a five blade wind graber might get going faster and work out better. What are your thoughts? What is the expected cut in RPM on the 500?