so:
perspex has this wonderful habbit of "crazing" when it gets hot then cools rapidly (winter) so i reckon those covers will last about 6 months before they are cracked to ****, THEN when they crack their structural integrity will be reduced significantly and oil will start to weep, plus they will cloud up in a few days due to the abrasive nature of fluid running over an object.
not to mention the fact that the hole spacing between the bolts that fasten the rockers on is BARELY enough to keep a cork gasket sealed with an ally or SS rocker cover when you start building up crankcase pressures from high heat and high RPM. if the mounting bolts dont outright crack/perish, then the center of the gap between the bolts will certainly flex and youll have lovely oil running all over your shiny new extractors.
id love to see a vid of these covers after 2 weeks of daily use.