Get gages first of all so you will know what is normal etc. Next the boxes that advance timing are great because they increase power and fuel milage. Some even give you a little more fuel as well. All the fuel mods in the world wont show their true potential until injectors are changed to allow that extra fuel to flow.
Gages first, exhaust brake, timing box (such as The Edges "EZ") then if you still hunger for power, injectors, but keep in mind alot more fuel means more air in, and more air out will be needed as well.
Everyone has a ritual they like to follow that works for them, and this is the one I think will work for you. Hope this helps.
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