If the wattage for the new system is similar to the old system then there shouldn't be a need for any fancy wiring. Putting in a larger fuse is always a no-no especially if the fuse size was determined by the manufacturer. They do this considering the draw and some room for additional load. Increasing the size of the fuse may allow too much current to flow and, over time cause overheating. If a larger fuse is needed because the fuse keeps blowing in the case of headlights or fog lights then put in a relay and put the coil on the circuit that used to supply the lights and wire the contacts of the relay in a switching configuration directly to the battery and then to the lights. The wiring to the battery should be sufficient to carry the load of the lights as well as the contacts of the relay and should be fused appropriately. Remember, the aim is to produce the desired effect without causing a fire in the vehicle.
Participate in life....Keep movin'....Go there....JK'n it.........Do it! Jeep #1: Red Rock 08 JK Rubicon 4dr, 6 sp manual, Stock Mud Tires, MyGIG Upgrade, Hard Top, after sale BestTop SunRider Soft Top, Congo Cage Rack, Mopar slush mats Jeep #2 Black 08 JK Rubicon 2dr, 6 sp manual, both tops, some chrome...uggg (my wife's jeep) Jeep #3 White 92 YJ (my son's jeep) A great quote from a good friend: "All hail click clack and master jk'n." Click and clack are my idols!