I've noticed my AIS pipe has rotted through in places down near the exhaust. Will this harm the engine or the cats in the stock exhaust? Ideally I'd remove it and fit a blank plate but given its location and the state of corrosion I'd ideally need to drop the engine as I'll be amazed if something doesn't shear off.

What are my realistic options and how harmful is it to run the engine with the holes? I'm looking to apply metal putty to the holes for the time being.

The valve is after the ais pipe, so the engine is not sealed off. I'd say close it up. You'll probably have a noisy engine right now because of it