Hyundai Repair: Exhaust manifold, emissions test, oxygen sensor


Question
I have a 2000 Lantra Si 1.6l  UK edition (right hand drive) I was told by my mechanic last time I had the car serviced that there was a leak in the Exhaust manifold, but according to his parts catalogue there should be two separate parts, whereas my car has one combined part, which means official Hyundai parts only, the car might not pass the emissions test, so would need fixing. Other then mild extra vibration when I drive over 85mph the car is smooth and runs normally,  although does loss power when I floor it, (so I don't), and  makes a "put put put" sound when driven slowly when the engine's cold.How much can I expect to pay for this repair and what else might be go wrong as the result of the leak?

Answer
Since I'm in the U.S. and have no idea of U.K. economics, I cannot even begin to speculate about the cost of your repairs.

On 2000 Elantras in the U.S., the manifold is in one unit with the front catalytic converter.  I do not know whether this is the case for your car or not.  If you'd like to follow up with your VIN, I can try to check the Hyundai parts catalog.

Your power loss and put-put-put sound like a misfire, so I'd recommend checking the secondary ignition system (plugs, wires, coil).  

As long as the leak in the exhaust manifold is small, there will likely be no consequential failures beyond perhaps the check engine lamp illuminating and storing an oxygen sensor code.  If your lamp is already on, you should have the trouble codes read and diagnosed, as they may be related to your put-put and performance issue.