I had the faint ticking sound for a short bit, not loud at all but the common sound that so many people seem to get. Just recently it started making more of a "tapping" noise from the engine once it warmed up, loudest around 2500RPM. I only drove it a few short trips once it started making this noise. Last time I drove it everything was fine, then right as I was coming home it suddenly got louder. I pulled into my driveway (which is steep) and as I was balancing the gas/clutch to slowly go up the hill I stalled out like a bozo. Well, it wouldn't turn back on, because the battery was dead for some reason. So I charged the battery and cautiously tried turning the engine on. It started right up but it has a very loud knocking noise that sounds like it's coming from the drivers side top of the engine. I haven't pulled anything apart yet because I wanted to see if anyone else had any experience with this noise. I have been told by some car guys that it doesn't sound like a rod knock, that it sounds like valvetrain noise or the piston hitting something. The car is a 2012 GT, always well maintained, usually driven easily, oil changed on time, 69.5K miles. Only mods are an exhaust and X pipe. Here's a short video of the sound.