I'm wanting to put high flow aftermarket mufflers on the stock exhaust on my 99 GT. I've had full system rowdy exhaust set-ups on both my previous stangs so I understand that just an aftermarket muffler on a stock exhaust won't make a HUGE different in sound but I want it if possible close to as quiet as stock but being free flowing. Any help would be appreciated. Not Flowmasters. Thank you.