This is a question that is asked time and time again so I thought it would make sense to create an FAQ article.

The official Spark Plugs used for the Twin Spark engine from the factory (OEM) are as follows (click each to go to the associated NGK web page):-4 of each are required (so 8 in total) and they last for 60,000 miles (100,000 kilometres).

The cheapest place to usually find these are on eBay. Don't get them from a dealer as you will get charged ~120 for exactly the same plugs which are just put in an Alfa branded box.

While the usual advice is not to bother with cheap plugs due to potentially poor running problems and ending up more costly in the long run, there is actually another thread HERE which specifies some other plugs that have been tried and tested with the TS engine.