Re engine box, the instructions for the kit were altered to recommend the glass of the front with thin cloth. Properly fixed and glued this step is not necessary but we had one customer who had a problem so the instructions were changed to recommend and not to be an option.
I cut out the holes too and have not bothered to fill the in/cover them over - havent considered it necessary.

Foofy - in view of your comments I would go IC yes - and defo YS 140 power ! Im very happy with mine.