The DeLorean air filter P/N102575 element is located inside the black air box P/N 101058 on top of the engine. The air filter should be inspected at every oil change and serviced at every major service interval (30,000 miles). In the case of a seldom-driven car, inspect the filter at least every calendar year.
Remove the three M6 bolts, [10mm hex], that hold the box in place and disconnect the Inlet Duct P/N 105927 by pulling the plastic collar off of the air box, and the PCV (Positive Crankcase Vent) hose to lift the box away from the engine. Unclasp the four wire clamps PN 102581 that hold the box halves together to gain access to the element. Replace (or clean and oil, in the case of the K&N) the air filter, put the box back together, and re-install the air box with the three mounting screws and washers. It's really a lot easier done than said. New filters, air boxes, clamps, DMC label, and inlet tubes are readily available.
There is a Performance Air Intake P/N GT100200 hose available which replaces the paper duct, plastic tube, and preheat valve. This also eliminates the often-discolored metal preheat tube and rusty manifold heat stove. This is the same system included in the Stage 1 and Stage 2 Engine Kits.
To install this intake, remove and discard the metal preheat tube, the paper intake tube, the air inlet diverter valve, the plastic elbow at the body, and the metal bracket. The rubber ends of the air intake will fit the original plastic air box adapter and will pressure-fit the hole in the body. If the plastic adapter is missing from the air box (it is no longer available) the rubber collar will press-fit into the opening of the airbox rather than around the outside. With some effort and a longer screw you can re-use the original body bracket for added security.
Updated 6/7/2016 DAS [details and links]