I am in the process of refreshing a 98/99 Triumph 955i (not badged as a t595) and decided to do the plugs. They can be areal PITA to be get out due to the fact that the Originals were apparently NGR DPR8EA9 from the factory and the guide indicates replace with NGK CR9EK. A search on ebay also reveals lot of potential alternatives but I wanted to make sure my new plugs would match original specs Fortunately I found a guide on the BIKERATE website that gives a good breakdown of the plugs for all triumphs including the Daytona so I thought I would share. I have attached as files but url is below too https://bikerrated.com/gear/maintenance/triumph-spark-plug-fitment-chart/ https://bikerrated.com/gear/maintenance/triumph-spark-plug-fitment-chart/