Jack,
I agree with Sparky, just having them stick out the side is not to "aero" and then not pointing them to the rear is just like throwing away horse power. Just to do a quick calculation with some easy numbers let's assume that your exhaust produces 25 lbs of thrust, which might not be to far off for a small supercharged engine, at 200 mph that is 133 horse power! Can you afford to do that?
I have always like what the Contrivance Engineering guys do with their exhaust.
Rex