Ok to start out I feel it necessary to let you know that this is actually for my friends 2013 police auctioned Charger. He likes buying these cars at auction. Sometimes you win other times not so much. His most recent was a police charger that is actually not the police model but an RT. On his way across country with this new purchase he decided to let her rip. He reaches 120mph when all of the sudden it lost a few hp. It still drives normal just seems weak. No engine codes are showing up however he revels it for me and it sounded like a rc car. It no longer sounded like a reved hemi but rather my wife’s old Honda Civic. Someone told me there’s some sort of valve in the plastic manifold that may have gotten stuck causing the whine of a 4cyl and low hp but I’m not so convinced. Any help would be fantastic.