These mufflers are exactly what you expect from flowmaster, they sound great when you want them to and are much quieter at cruising speed than the original 40 series. I bought these for my 2003 Mustang GT and they were almost a perfect fit, a little shorter than the stock muffler and the in/out are 1/4" larger than stock but that matches up great with an aftermarket x-pipe and tailpipes. They also shipped very fast, arriving in less than 48 hours with the free shipping. I can't speak for many other models but if you put these mufflers on a 4.6 mustang you will not be disappointed.