Powerful Sound with No Drone! Bolting On Ford Racing’s FR500 Mufflers For ’05-’09 Mustang GT and GT500

2005-’09 Mustang GT’s and GT500’s all use the same muffler with slash-cut stainless steel tips. Theses mufflers have a good mellow tone and flow quite well for factory original.

We love many things about S197 chassis Mustangs (2005-2014), but one of the best is the simplistic muffler swap due to the mounting of the mufflers to just behind the rear bumper cover. This was primarily done to relocate the fuel tank to in front of the rear axle for better weight distribution and overall crash safety, but it makes life easy for us!

We always endorse safety here at OnAllCylinders, so after using the rearend housing to lift the rear of the car via a hydraulic jack, place a jackstand on the axle tubes on both sides of the car.

Rather than being welded into place, the mufflers on Mustangs are secured with a large band clamp that is easily released with a ratchet and socket. It’s almost like they knew this swap was a given! Loosen this bolt first.

There are two rubber isolators that the mounts from the muffler hang from. This one is located at the inlet of the muffler. There is one bolt that goes into the bottom of the framerail, and one 90 degrees from it just inside the isolator. It’s possible to leave the isolators bolted into place and wiggled the muffle rout, but it’s far faster and easier to just unbolt them.

The second mount is at the exit side of the muffler just inside the bumper cover. Just like the forward mount, there is one bolt on the bottom of the framerail and one just inside of the isolator. When these are removed, the muffler will droop slightly, but the tailpipe will hold it in place.

With the clamp loosened and the isolators unbolted, it’s only takes a few small wiggles and tugs and muffler will slide right out. At this point we’ve spent maybe 10 minutes on the job! (Image/Christopher Campbell)

Here is the stock muffler next to the FR500. The large size difference is the most noticeable change, which actually reveals another big benefit of this upgrade over most; weight reduction. (Image/Christopher Campbell)

The stock muffler weighs in at 16.5 pounds, or 16 even without the isolators installed.

The FR500 mufflers, however, only tip the scale at are just a bit over 12.25 pounds. That’s an 8-pound total reduction off the rearmost part of the car. It may not sound like much, but that’s a big deal in the racing world these mufflers were designed for.

The stock isolators slide onto the FR500 mounts and installation is as simple as sliding the muffler inlet pipe over the exhaust and bolting the 4 isolator bolts back into place. Looks at all that extra room! Install actually goes so much faster than removal since the FR500 muffler leave so much room for swing a ratchet. Tighten the isolators, but eave the inlet pipe clamp loose for adjusting the positon.

Once both mufflers are installed, use the rear bumper cover as a reference point to slide the muffler back and forth a bit to ensure they extend evenly from each side. The passenger side pipe has a handy indexing notch that establishes depth, but the driver side will need to be adjusted to match.

The perforated holes inside the FR500’s exhaust tips are part of the key to its droneless demeanor since they work to change the frequency content of what comes out the tip.