I have the 2500HD 4x4 crew cab Classic style for only two days and I need to mod. First, new dual exhaust. Second, new wheels and tires ( 20" or 22" ). I plan on towing to the max ( 15,500 or more if possible ). What is the type of wheel I should be looking for to maximize the towing? Also more power wanted, are new injectors worth it without voiding warranty with a "chip"?