The P webpage in my sig has the part number for the short plugs, but they are outrageously expensive. I would recommend getting some MSD plug wires (or any brand for that matter) with a 90* boot on the end. The 90* boot ought to allow plenty of clearance. Not sure on lifting the engine. That would probably depend on the condition of your motor mounts and who knows what else. I have heard people say they had no poblems. But I have also heard of having to jack up the motor just a little. Another thing I heard was of some people installing the headers from under the car. I don't know which will work best for you. When I get mine I will just attempt them from the top.
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1991 Mustang GT - Cobra Intake, FMS 65mm TB, C&L 73mm MAF, GT-40P heads, Crane 2031 cam, Crane 1.7rr, Built AOD, Art Carr 2400 non-lockup converter, Transgo shift kit, BBK chrome cold air, FMS 'P' headers, Pacesetter off-road H, BBK aluminum pulleys, 2-C Flows w/ dumps, 4.10's, Steeda STB, for now...
The Original GT-40P Tech Page