Ive been having a continuing issue with my tacoma. When im driving (especially under load) i can hear a exhaust type noise through my passenger side firewall. The noise is not heard if i have it in neutral and rev the engine. which i would describe as a chugging more than a ticking. however there is a different noise thats coming from what i think is the cat, but i have no codes thrown. This used to be my brothers truck and the manifold was replaced with another cast iron one (yeah i know) but i dont think it would have cracked already its probably less than a year since he replaced it. any thoughts about this? im sorry i cant be more specific, i really cant place what it sounds like. I have a sound clip of what ive been told is a cat problem but its an .M4a so i dont know where to post it. if anyone really wants to help i could email the clip. Thanks.