We’ve been Mustang enthusiasts for quite a while and have attended hundreds of Mustang events. That being said, we’ll venture a bet that one of the first performance modifications made by a Mustang owner is to install a set of Flowmaster mufflers on the new ride. While the factory exhaust system does get the message across that you’re packing a V8, the distinct sound of Flowmaster mufflers ensures that everyone knows it. When the 2010 Mustang came out, we decided to do a quick Flowmaster install to see how the Flowmaster sound and performance stacked up on Ford’s newest Pony.
Flowmaster has been building Mustang exhausts since the mid 1980’s, and they’ve spent countless hours perfecting the sound of their Mustang exhaust systems. That “Flowmaster Sound” is recognized not only on the streets but also at the racetrack as the manufacturer has been very supportive of grassroots drag racing.
As any new Mustang owner with a performance pulse wonders, we were curious to see how the 3-valve 4.6 Liter Modular engine in our 2010 Mustang would sound with a Flowmaster exhaust. We decided to pick up the phone and order their S197 Mustang Stainless Steel Exhaust System – Part Number: 817460.
The Exhaust – Mustang Stainless Steel Exhaust – Part Number: 817460
We got right to work on installing a new Flowmaster 409S Stainless Exhaust System on our Sterling Gray Metallic 2010 Mustang GT project car. Out of the box, the bolt-on system included two American Thunder “Classic Series” Mufflers and stainless steel exhaust tips. The Classic Series mufflers are duplications of Flowmaster founder Ray Fluggers’ original square “Suitcase” mufflers that started it all.
The mufflers are hand-crafted and formed with the original tooling that has been in Flowmaster’s production facility for 25 years. Unlike the originals, however, these units are constructed with 409S stainless steel in order to last a lifetime. The square muffler case with its wider profile produces an extra deep tone that helps broadcast that trademark Flowmaster Sound.
Stock Muffler Removal:
The first step in installing our Flowmaster axle back exhaust was to get the Mustang up in the air with a lift or jackstands. After the car was on the stands and cooled down, we sprayed some penetrating fluid (WD40 or Liquid Wrench) on the OEM exhaust bolts to aid in their removal. Fortunately, our 2010 Mustang’s exhaust bolts were a cinch to remove and didn’t really require the fluid. However, if you’re working on any Mustang that’s a year or two older, spraying some penetrating fluid on the bolts is highly recommended in order to aide in easier removal.
Next, we grabbed a wrench and a 15mm socket to loosen the nuts on the OEM clamped pipe connection between the mufflers and the over-axle pipe. Once the clamps were loose, it was time to move on to the muffler hanger removal. The Mustang muffler has two reusable rubber hangers that mount it to the frame, so we were very careful not to tweak the hanger assembly during removal.
A 13mm socket was used to remove the bolts that secure the muffler hangers to the Mustang frame.
After removing the two hangers on each side of the frame, we slid the OE muffler off of the over-axle pipe and set the factory muffler aside.
With the hanger bolts easily accessable, we removed the mounts off of the stock muffler and put them onto the new Flowmaster mufflers.
Before we started reinstalling the new parts, we prepped the clamps supplied in the Flowmaster hardware kit by removing the nuts and applying lubricant to the threads. This makes for smoother tightening during the installation process.
We then placed the supplied Flowmaster ring clamps onto the inlet pipe of the Flowmaster left muffler and slid the muffler onto the OEM over-axle pipe. The left muffler hanger mounts were then put back into position on the frame, and we reinstalled the factory bolts. To tighten the hanger bolts above the muffler, a 13mm open end wrench is the best tool to reach the bolts.
Once the hangers were in place, we leveled the muffler with the exhaust piping and tightened the clamp on the muffler inlet enough to hold it but still allow for adjustment. We repeated the process for the right muffler and prepared for the final adjustment.
Once the Flowmaster mufflers were in place and semi-tight, we adjusted the position of the mufflers for final tightening. We checked the position of the exhaust tips in the Mustang’s rear fascia exhaust cutout. Keep in mind that the tips do generate heat, and if the tip is too close to the rear fascia material the paint and fascia will burn. Flowmaster says a minimum of ½ inch clearance around all parts of the system must be maintained. This clearance is also applied to suspension parts with potential noise and vibration in mind.
After the final adjustments were made and the clearances were checked, we securely tightened all clamps.
With our project Mustang still on the lift, we fired up the engine, checked for any possible exhaust leaks, and soon cracked satisfied smiles after hearing that trademark Flowmaster idle. Revving the engine created that awesome chambered muffler sound we’ve all come to appreciate. We eagerly took the car out for a test drive to check for any squeaks and rattles and excitedly noted that the exhaust was around 15-20% louder than stock. Mission accomplished!