I have a 2012 V6 MT. I was concerned about pinging or metallic type noises when I shift around 4k RPMS or higher. I have no resonators on mine, so exhaust is somewhat loud It almost sounds like a TON of clutch chatter, but only happens in higher rpms. After revving it high in neutral, it's just some tin/metallic type noise resonating from the exhaust. (@ 27k the exhaust note is different, which is expected) If it's under warranty and stock taker on in. I'd check the basics first though, such as air filter, clean MAF, fresh gas, and PCM reset to see if it resolves the issue.