I recently installed a new Megan Racing axleback exhaust on my 2010 3.8 Genesis Coupe. With the stock exhaust, revving to about 2-3k rpms and letting off produced some pops, but with this exhaust, I instead noticed that where the stock exhaust would pop, this one tends to give some strange vibrations, 1 or 2 strong half second long vibrations as the rpms drop, in place of the pops. Is this normal? I don’t think it would have anything to do with my engine mounts, which appear to be fine. The car is otherwise fine, and this only started after replacing the exhaust.