I use Grease Lightning on everything in the egine bay except anything that is Polished aluminum. I use a mix of 50% GL and 50% water in a spray bottle Leave it on for maybe 5-10 min then rinse off. It comes in a gallon container and is 1/5 the price of Simple Green. You will not need to wipe much off Grease lightning lifts most grime unless it is caked on.
at work we use a "special" cleaner, haha and a power washer... only on chevys and hondas we worrie about getting things wet, a mustang is ok to wash just to go puttin 100 gal of water on there and make sure your engine is cool,