Karl; I have the Spychalla Cowl and Tony Howard Exhaust for my Stang; as far as the Muffler, Revo sold me one that was made for the TF P-51, no cutting needed; one question, or maybe two; I know you probably had to make a hole in the firewall for the Carb, besides that hole did you make other holes to vent the air flow through to the Fuse or did you make the Carb hole bigger?

I actually came up with an idea to use a product called Therma-Cowl from Oregon Scale Products http://www.oregonscaleaviation.com/R...hermaCowl.html ; its a heat thermostat operated unit to open Cowl Flaps when the temp inside a cowl reached a certain temp; my thought was to use it to open the Oil Cooler Vents on the P-51 when the temp inside the cowl reached certain temp, probably when on the taxi way etc, and possible close once in the air.

Like yourself, I was planning on making Oil Cooler Vent door to access the Switches, Charge Jacks, Air Fill, etc; you have these in your Vent area, do they impede the air flow you are trying to exit?

Doug.