With the low resistance wires you should probably increase your plug gap about .005" from stock otherwise the system will not be able to consume all of the available voltage and you spike the ignition coil, over time this will cause it to overheat and fail.
If you get a performance coil, like an SS Blaster coil or something also increase the plug gap another .005" to prevent the same problem. If you go with an MSD box or other big ignition upgrade change your plug gap to whatever is recommended for that system by the manufacturer.
I have never seen a performance wire set improve economy over stock wires, though they are useful in high RPM applications.[/b]
That is because most people do not increase their plug gap to increase the restistance between the spark plug gap to be able to use the power. Every time the primary circuit closes all the power that isn't consumed gets disapated in the coil via a small power fluctuation that causes heat. Every component in the secondary system has resistance which consumes power, the coil wire, rotor button, gap between the rotor button, distributor contacts, plug wires, spark plugs, plug gap and the return ground path back to the coil all consumes power. The trick is you want all the power you can consumed accross the plug gap, the more power there is to consume there the more you can increase plug gap which gives the spark more area to ignite fuel. Putting in low resistance plug wires frees up more voltage to be consumed between the plug gap but without increasing the gap it will consume the same amount of power regardless of how much extra power is getting to it. On old worn out ignition systems performance wires often help because old spark plugs take more power to get spark so performance wires will help jump the gap, same goes if the ignition coil is weak the wires will help make sure all the voltage from the coil is making it to the plugs.
A lot of your newer high end cars if they still have plug wires already have low resistance wires from the factory.
Waste spark systems have even lower resistance because it puts two plugs in parallel, and the total resistance in a parrallel circuit will be lower then the lowest branch in the circuit.
Removing the tail gate is no different from putting it down it will cause drag because the vortex of air behind the cab cannot build to keep faster moving air off the truck. Without that vortex the air comes down and hits the bottom of the bed creating drag.