valve train noise?

[kirbyman03]

just got a 98 ss 36k on it. has fully ported heads, headers, cold air intake, 224/564 cam, has factory rockers im changing them today, ls6 intake. sounds like lifter noise to me its clattering from on top gets worse with rpm , runs real hard though. never had an ls1 before is this normal or something serious my mechanic said its just from the cam and is normal i dont know my super gas car didnt make it with a larger cam. could be bad lifters? and how do you tell if they are? come on guys help me out here !!!

[01stngkiller]

my vavles make a fluttering noise at about 2500 rpm, especially when its a little cold. i think its normal though. so dont stress too hard