I have heard nothing of this anywhere, and it is not on the website for RB Products either. Are you sure you don't mean the new RB Concepts S7 II? The S7 is a 7 port, why would they goto a 5 port? more low end? If so, seems silly as the WS7 II and the S7 II already are known for low end torque. Where did you hear this from?
UPDATE - I just found the engine on ebay, with a picture of it and the box - it does exist. Never heard of it before - says its supposed to be for small tracks. Weird.