Just an FYI and my opinion. I recently started my 03 ST4S after the winter. I had started it a couple times throughout the winter but had not ridden it. Long story short the spark plugs fuel fouled. I replaced the Champion plugs with NGK (R-2525-10). This made for a unbelievable difference. Even compared to before the original plugs fouled. The bike doesnt even turn over one time before it fires up. Very good investment and I would recommend to anyone looking to change plugs. The plugs came from sparkplug.com. They were $10 a plug cheaper than I could find local (still $27 a plug).