This is a DA85 with a Silent Beauty TBM pitts style muffler. I was hoping to have the pipes come out behind a cowl flap cut out of the cowl but this is what I need to do to get the cowl to go on. Will the exhaust pipes themselves make this enough of a low pressure area to cool the engine. I will be adding ducting in front of the cylinder so that all the air that comes into the cowl will flow over the engine's fins.

A ridge, ramp, or low pressure device needs to be ahead of the hot air exhaust opening to have any effect of draw. If you can ramp some inlet air from the cowl inlets towards the bottom of the head what yu have should do. Barring that, you have a strong chance of being very marginal in hovers, torque rolls, KE spins, tail slides, and tumbles. ll of which are hell on engine cooling.

i think something like this can help more... not too fancy or scale....but work better, what do you think T.O.M.

If you open up the cowl like pictured, and place an airdam at the rear op the cylinder, you create an airflow THROUGH the cowl inssted of OVER the cowl.
Next required step is to make a baffle in the front 1/3rd part of the cooling fins, to force the air THROUGH the fins, instead of AROUND the fins.