I know its totally not what people are advising you to check. But I got a weird metallic sound from the spring kit where the exhaust manifold downpipe met the midpipe. What has happened is the lead ring deteriorated, causing slack and the spring kit being worn, rattled around and made a "pebble in a tin can" sound or whatever. That happened in low rpms when u put the foot down going up a hill.. This is for D16Y7... so, might wanna just check that its not loose there intead of going through all the hassles of valve lash (not that that's not a good thing to do anyways once in a while)