Gunk Citrus Engine Detailer is good stuff.
I just started using 50/50 Simple Green-H2O and throughly soak then engine compartment, (with elect stuff covered), let soak, then wipe everything down with a rag and hose off.
Then spray GCED everywhere, let sit for 30 minutes, then drive the car.
Looks great with out the greasy dust collecting residue other products leave behind.