I saw on in McBride this year, It was still being tuned so it wasn't running well. He said that the second turbo was there to pick up the lag you get before acceleration rather than adding more power. It was a small mitsubishi turbo.
Yep, what he said. As far as I know, they are using a smaller one to spool quicker for the big one so that there is minimal lag with the larger turbo making more boost. I have heard 500 HP, haven't heard of anyone with one though. Should be fun to ride.