Da rock
I did the same thing to my GP Skylane as you did to your cap speed was not a design goal but I wanted the motor to get better cooling than just cutting out the cowl openings and dumping the air into the cowl. A bit of foam and balsa made for light baffles and worked well.
My cub cowl is a bit more aggressive...
This was not designed for speed just wanted it to look good, and work well, as I told Mike the hardest part was setting up the exhaust which I ducted through the fuse.
Mike,
That chapter has been sent to you.