I powered my Aurora with a YS91FZ. The tuned pipe is quiet thin compared to a 2 stroke pipe, therefore I did not how a grove in the underside of the wing.

The YS cylinder head pokes out the top of the cowl. Even with the small triangle air scoop in the front of the cowl, the engine always runs cool. There is a small amount of heat build up with the enclosed tuned pipe, but nothing extream.

Mike