Hi i have just had some supertech valves installed in my B18C. Ive had a look at the stock valves and one side's(EX or IN) seems to be smaller(from the face side)and has an "F" on them whilst the other says nothing? what side are they for and are they stock valves?

 

The intake valves have a larger head diameter than the exhaust.They sound like the stock valves.
Glenn

 

Thanks.. Its just the smaller side that had F on them that confused me, because the other valves had nothing written on them