2000 is "vintage" now? Dont think so, especially not in the context of VW Beetles

If this is the Golf-based "neo-Beetle" it'll be burdened with a catalytic converter. so a "new exhaust" might well make a difference, though probably not necessary.

If its a classic air-cooled Beetle (perhaps Mexico-produced) it might still have a catalytic converter as a late model. If it doesnt have a catalytic converter a new exhaust wont make any difference to emissions, unless the exhaust is blocked and interfering with engine breathing

If its cat-free. it either needs a tune, or it needs rebuilt. You might try new plugs and removing the air filter temporarily .

EDIT : Sorry, missed the "three year old cat" bit, so that answers that.

Its possible its running rich and so has killed its cat, which I'd have thought should last more than three years.

I suppose ones next move might be to get an OBDII reader and check your fuel trims. but I have no experience with all that OBD catalytic converter stuff.

If you just replace the cat without diagnosing and sorting the underlying problem, your replacement likely wont last long

Edited by edlithgow on 13/09/2023 at 02:37