snmalone

I have a 04 EDM AP1 with an F20 engine which ran about 74k miles. No Oil consumption, engine runs fine and ok power. What i have is when the engine is warmed up and you drive it there is a certain noise, kind of valve tapping, you can hear it best when you roll without putting down the throttle. Its the loudest when i drive downhill and the engine idles at low revvs. Its clearly louder, i didnt have this noise on my previous 3 s2000s. It had some aftermarket cams installed from the previous ownder for a while which i dropped. the noise became quieter afterwards but it is still there. any idea what it could be? compression is not like brand new but ok and the same on all cylinders. what could be worn out on the head to cause this noise?