RE: Smallest RIRE engine
It's hard to imagine scaling that idea down small enough on a .40 sized speed ship. Take the current level of performance with just a tuned pipe, add forced induction and then the pipe becomes the limiting factor unless you increase it's size I suppose. Adding girth to the pipe makes it fatter than the engine which isn't good. As usual, it looks like an idea where you realize certain gains if you can figure out how to limit the losses.