I restarted and taxiied away from the hangar a bit so as to not be as loud for others in and near the hangar and did a full power runup.  I hit 5600 static rpm's. In the past, the best I could hope for was 5200
Paul, if you get that much of a change by just installing the cowl it is probably not the heat. I would make sure you aren't restricting the intake. This is far moer likely to cause a instant RPM drop. Be sure that there is enough room for the air to pass! If not cut a hole in the cowl and put a periscope scoop on the thing. You may even get some ram at speed improving the performance. IT IS THE SIMPLE THINGS THAT ALWAYS BITE YOU. Good Luck.
Bill Jepson