Thats not a bad description. Its pretty open and you can see right down inside to the box portion. It would have to be bigger and baffeled in order to decrease the noise.
It was running next to the house idling and then I walked around to the back yard and it was noticable but not too loud. At full power for a couple seconds it was very loud standing behind the plane.

The engine comes with exhaust tube extensions for larger cowls but this would not help quiet the noise.

The rear exh. version is supposed to have slightly more RPM than the side exh. version. The side exh. version offers more quiet pipe options.