conanski said:

What tube are you referring to, the one that goes to the cats?

The whole air injection system is superficial to engine operation, it's only purpose is to provide fresh air to the cats to help them burn off excess hydrocarbons at cold start.. that's it. As a result you can completely eliminate the system without affect engine operation or even throwing a code, but to do that you need to remove all the tubing, plug the holes in the back of the heads where the crossover tube mounts(5/8" coarse bolts), and remove or plug the vacuum lines between the TAB and TAD solenoids that control the diverter valves in the system but leave those solenoids electrically connected. All this is necessary because you absolutely cannot have any fresh air leaks into the exhaust system upstream of the O2 sensors once the engine hits operating temp because that will cause it to run excessively rich, and crimping a metal line isn't sufficient to completely plug it. The point on the exhaust where the air feed tube connects to the cats also has to be plugged but often this whole issue comes up when replacing the exhaust and in that case this part won't be a problem.

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