What happens to the "waste" produced by ship's engines?

[Carlobrand]

Well of course, one can argue how many AUs X energy output is detectable, etc.etc., but the rules are what they are, for gameplay reasons, and so IMO the thing to do is to assume the technology does indeed somehow dampen/screen/absorb/use all that IR such that the ranges are 'right'.

A time-honored scifi tradition of making the tech fit the story.

Ayup. I've been playing around with the idea that some property of the maneuver drive created an interface zone outside the ship where outbound photons converted into quark-antiquark pairs or perhaps converted into gravitons. Don't know enough about the physics to make it work, though.