Thanks for the friendly words guys! Sorry if I have offended the purists!
CHT temps were up around 410-415 F oil up to 210 in climb.
Have Showplanes cowl, 10:1 Pistons on a Superior IO360, James plenum chamber (modified to fit and seal properly), standard Vans oil cooler.
OAT was around 70F at the time of testing.
P-Mags were set to 25c.
Everything looked to be set up right, but the temps were too high.
I added the louvres to get the problem solved during flight testing to get the permit to fly.
It worked. CHTs now steady and balanced at 370-380 in climb, oil no higher than 180.
I saw no noticeable reduction in speeds, so drag penalty seems low. Why not keep these on permenantly? They don't look too bad (pretty good actually).