Here's what i did on my car in order i did them. It was fully stock when i got it.
Full tune up, changed worn steering parts, NGK plugs, Magnacore Wires, INJEN Cold Air Intake, D2 Suspension, re-fabricated the interior, Optima Red/Orange Top battery, Apexi cat back exhaust, valve cover gasket, ... thats it so far. Looking into new timing assembly and new head gasket.