Online parts fiche are a good source of info to:
http://www.ronayers.com/Fiche/TypeID..._CYLINDER_HEAD
This gives you the various plug choices available and shows 2 per cylinder. Obviously you don't need to order as Suzuki parts but it gives you the plug manufacturers codes for you to search online. Not bought for a wile now but there were some good discounts online for buying plugs especially when buying four.