Gordon, my heater exhaust cannot be seen. It runs inside the beam and protrudes from the aluminum undertray about a 1/2". The exit is the only part that can be seen. The exhaust exits right into the slipstream of air under the car. The combustion intake air is from up by the fuel tank and has a muffler on it. The muffler came with it and quiets the "roar" a good amount.
My cabin/heated air intake is from inside the driver's rocker panel, that way I don't have a heat loop. I still don't have a top so it doesn't really matter where that air comes from as long as the intake air doesn't warm too much(like if I had a top!) the heater never shuts off.