Swede,Sorry! This is my first look at your project.
I like what you're doing.From an airflow standpoint the only hitch I might think of,is how the sides 'tumble' aggressively from the cab back,falling at an ever steeper angle in such a short distance to the back.
Tuft-testing will reveal if flow is good there.Hope so.
Otherwise,you should be rewarded for your efforts at the pump.Nice work!
