Attached is a log and csv from FBO testing (2 days after AA intercooler install). I also had a video from this and it was making the noise during this log. I'm going to go back through my video's to determine roughly when it started becoming more apparent but from memory, it was when i started running e85 and obtaining higher boost.
I prefer to leave the cowl off and run the bms cabin filters. This way, i can listen to and diagnose the engine if needed, it keeps the temps a littler lower in the engine bay and its a weight saver.
I like the theory but based on all my logs, i've never really had an issue with AFR...