I got the advise below from John Taylor in Phoenix Design:
"The main object of the Unique storm Cover gives protection not only to the cockpit when the hood is either up or down but the bonnet vents as well.
This cover prevents rainwater entering the engine bay which is more of a problem with the Zetec engines. The rainwater collects around the spark plugs and gives rise to starting problems. Also we had problems with the +8's where rainwater collected around the coil.
However, there not being much difference in price , I've always recommended the Unique Storm cover as it covers all options and with more straps is more secure in high winds. The cockpit covers as with all other makes tend to 'balloon' in high winds."
