I just got my car back a few days ago from getting the motor replaced because I threw a rod after hydrolocking and this gosh awful sound comes from my intake when I accelrate. It is soo loud that it over powers the exhaust and intake combined. I took my car back to the mechanic and he said he had no idea what the noise was. I put my stock box back in and the sound went away. I just put my intake back on and its back. It sounds like rapid knock. Like my pistons are hittin or the valves need to be adjusted or somthing broken is flying around. Ill try to find a way to record the sound.
Any ideas what it could be?