i noticed today because i hauled ass out of a gas station. i got around 4k rpm and i heard a really loud fast knocking. so when i got home i open the hood and gave it a little gas. knocking starts to get loud at around 2k rmps in park. so i did a little research because i thought it might be a rod but i read if i hold the brake and go to about 1800 rmp and the noise gets louder then its probably a rod. but i did that and i couldnt hear knocking at all. everything is bone stock from the factor as far as i know. except for low resistance spark plug wires and a high output distributor.