TESTED: Ford Performance Cat-Back Exhaust and GT350 Valence

The Ford Mustang may be the best-selling sports car in the world at the time of this writing, yes you read that right, but it is far from the best sounding sports car in the world. We reached out to Ford Performance for their far more attractive and aggressive M-5200-M8TBV Touring Exhaust System and GT350 lower valence with integrated quad-tips to improve the looks and sound of our S550 Mustang GT.

The S550 Mustang GT leaves a lot to be desired when it comes to the looks and especially the sound of the stock exhaust. This was a major complaint in my review of the 2015 Mustang GT. Thankfully the Mustang has arguably the largest aftermarket parts industry with countless offerings that can solve this problem for us.

Our 2016 Mustang GT California Special is relatively stock other than the addition of the staggered Performance Package wheels wrapped in Continental ExtremeContact SPORT tires and an actual, real OEM carbon fiber GT350R wing that is manufactured by Multimatic. We were looking forward to replacing the boring and anemic looking stock exhaust.

With so many options on the market, it can be overwhelming and difficult to make a decision. One of the most important things when modifying any aspect of a car is to define what the goal and what the intended use for the car is, then do some research and make a decision accordingly. For us, our Mustang GT is a daily driver, so we wanted to make the car sound aggressive without being overly loud or drone on long drives, which can quickly get annoying and tiresome. This is a very subjective metric since everyone has a different tolerance level.

When looking at different exhaust systems, it’s important to understand the affect each component has on performance and sound. Working our way from the exhaust tips forward to the engine of a V8 Mustang, the rear mufflers are the most effective at reducing the volume of the exhaust. Forward of that is the resonator which changes the pitch and deepens the sound by reducing the higher frequencies of the exhaust. Removing the resonator gives the Mustang a higher pitch “trumpet” or “rasp” to the exhaust. Forward of the resonator are the catalytic converters. Other than emissions, cats knock down the sound (and power) of the engine quite a bit. Removing the cats alone will greatly increase the volume and usually pick up over half and often over 75% of the power gains typically achieved from long tube headers, which usually remove the cats in the process. Replacing the factory headers with long tubes further (and greatly) increases the volume and trumpeting rasp of the exhaust.

We can see the large factory resonator in the middle of the car followed by two massive mufflers and rather boring exhaust tips which flank a body-colored ‘diffuser’.

Since our primary goal is to have a comfortable daily driver that sounds more sporty, and with our preference of the trumpeting rasp found in most modified Mustangs and somewhat similar to a GT350, rather than a deep throaty burble, we decided on eliminating the deep sound-producing resonator with an X-pipe, keep the stock headers and cats intact and go with the quietest muffler possible. The Ford Performance by Borla M-5200-M8TBV Touring Exhaust System (designed for 2015-2017 Mustang GT coupe & convertibles) fits this bill by using their quietest muffler in conjunction with a resonator replacing X-pipe. Combined with the use of the GT350 quad exhaust tips and lower valence, I was sold.

I have to admit that I’m pretty fond of the GT350/R and especially the looks of the quad exhaust, not just because I’ve been fortunate to be involved with the development of the GT350 road cars and winning the 2016 IMSA Continental Tire Sports Car Championship in the GT350R-C racecar with Scott Maxwell, but because (as an objective car guy) I feel it’s one of the best looking and driving Mustangs of all-time. Ask anyone who owns or who have driven one, read the media reviews, or simply look at how many BMW and Porsche enthusiasts that bought GT350s, who would never have imagined owning a Mustang, and it’s pretty easy to see it’s a special car. I think it’s great that Ford is offering this GT350 valence and exhaust combo, and I personally don’t have a problem with people trying to improving the aesthetics of their cars with (high quality) components, short of simply slapping an AMG or ///M badge on a base car.

To kick off the exhaust swap, we first stopped by our friends at Palm Beach Dyno to get a baseline of our relatively stock Mustang GT before installing the new Ford Performance exhaust.  Palm Beach Dyno specializes in tuning late model Ford vehicles at their shop in Boynton Beach, Florida as well as remotely to cars all over the world. Since they know these engines very well, they were a great choice for us to accurately test and validate the performance gains of our exhaust.

With our car strapped down, we turned the rollers for the first time on our stock powertrain 2016 Mustang California Special.