Swaping engine.

...besides that, swapping in an engine that does not meet the emissions certification the vehicle has from the manufacturer is no different in the EPA's view as removing emissions components. Big fine if you are caught, and you may even find shops unwilling to work on it as a result because of what the EPA would do to them if the EPA found out your truck had been through their shop and they didn't report you or correct the "problem".

Far less hassle to just get what you've got overhauled or buy something old enough to have never had the emissions crap in the first place. Any replacement engine has to meet at minimum the EPA requirements of the engine being replaced.