Mustang Stainless Works Exhaust System (2011-14 5.0L)

It's been a few months and a few thousand miles since I installed my Stainless Works long tube headers with off-road exhaust extensions, and my Flowmaster Hushpower mufflers.

Time has come and gone for another exhaust upgrade. I really enjoyed the Flowmaster Hushpower mufflers on my stock exhaust. Once I installed my headers and catless lead off pipes, though, they got REALLY loud, and very raspy. In addition to the booming sound, the car's (illegal) exhaust was emitting extra fumes from the lack of catalytic converters. I also speculated that there was power lost through the car's factory 2 3/4" catback and factory resonators.

I discovered in my search for exhaust systems, though, that not all systems fit together properly. The Coyote's stock exhaust system allows for multiple placements and configurations of x pipes, and various options for the connection point of the catback system. Some manufacturers are installing the x in the cat-back, others in the conventional location behind the headers. Cat-backs from various manufacturers connect in different locations. This works if you're installing a stock catback to an aftermarket x or vice versa, but install an aftermarket header system from one manufacturer to a cat-back from another manufacturer, and you may find yourself at the exhaust shop.

Because of this, I looked to the source of my headers for a solution to my experimental, hodge-podge exhaust system. Anthony at Stainless Works exhaust obliged with a 3" x-pipe with high flow cats, and their Retro Chambered 3" exhaust system. He guaranteed me that the system would sound great, fit great, and mate to my Stainless Works longtube headers without customization or a tow to the local pipe bender.

I have to admit, I was skeptical when I saw the exhaust system. Back in the day, chambered mufflers sounded raspy and they popped. This is not the case with the Stainless Works system. 2 pairs of stainless, 3" chambered mufflers work to muffle the Coyote's howl, while minimizing rasp and droan. The car sounds amazing. It's quieter than the offroad/Flowmaster combination, the exhaust smell is virtually gone, and fit and finish is superb.

Mustang Header Installation Outline:

Stainless Works is a manufacturer of high-end, 304 stainless steel header and exhaust systems and components. Stainless Works’ headers are made from the finest materials available, to exacting specifications. Their 2011 Mustang GT headers for the 5.0 Coyote engine feature 1 7/8” primary tubes, 3” X-pipe with or without cats, and 3” lead pipes that mate to the factory exhaust, or aftermarket systems with stock-style connections. The 304 SS headers sport thick, 3/8” flanges and 3” slip-fit collectors. The system replaces the factory manifolds, catalytic converters, and H-pipe with a superior performing, lifetime guaranteed, bolt on system.

I’ve got to admit, we cheated a bit on the installation. We installed the headers while our transmission was out. Pulling the transmission is not necessary to perform the header swap, but it did open up room to access some of the tougher-to-reach bolts. This also gave us an opportunity to test whether the transmission can be removed and reinstalled with the headers in place. It was to our delight that we discovered that the transmission comes out just as easily (if not easier) as it did with the factory headers.

Our early production Stainless Works longtubes did not include an X-pipe, but instead connected to our factory cat-back with 3" extension tubes. All current Stainless Works header systems for the 2011 Mustang include an X-pipe in place of the earlier extension tubes. The customer may also choose to purchase the headers without extensions, if a custom system is in the works. We opted for the offroad version, but cats may be in our future to muffle the car’s tone a bit, and return it to street legal form. The car is deafeningly loud with no cats and our previously installed Flowmaster Hushpower mufflers. This is my only complaint. Otherwise, the headers fit better than any aftermarket header I’ve ever used. The thick flanges, combined with the 5.0’s improved 10mm header studs, are sure to hold gaskets in place and prevent exhaust leaks. The headers don’t rub or vibrate on anything. There is loads of clearance to remove the transmission, and there’s nothing in danger of being burned or banged against. Ground clearance is phenomenal.

The decibel meter says the car’s faster, but what about the butt meter? Well, I was simply astonished by the improvement in performance that the headers offered. I’ll have to admit, the large, 1 7/8” primaries on the Stainless Works long tubes scared me. In pushrod 5.0 speak, that’s huge. I was worried about a loss of torque from these sewer pipes.

Fortunately, my worries were unfounded. The car has more power everywhere. The air-pumping ability of the Coyote motor must need those big primaries. In stock form, the 5.0 didn’t induce enough power to lose traction without a deliberate effort. Now, if the traction control is off, you can just expect to engulf the Pirelli’s in smoke in first and second gears. Power is smooth and strong, all the way up to redline.

We’re excited to get the car on the dyno. With the combination of modifications we have, the car should easily crest the 400 horsepower mark at the wheels.

I’ve already been to the track with the headers, cold air kit and new tune, and I can tell you that the STEEDA cold air intake kit, custom tune, and Stainless Works headers resulted in some serious trap speed, and equally shaved some et. Our previous best of 12.22 @ 111.55 was blown out of the water. With the newly-added STEEDA cold air intake, Stainless Works long tubes, and tune, our GT ripped off a 1.54 60' time, blew through the 1/8th at 7.52 @ 94.95 and finished the 1/4 with a stellar 11.85 @ 114.95. We're confident there's more left in the car. We're still running the big 19" fronts, lowering springs, and otherwise stock suspension.

Before lifting the car, some work needs to be done up top. Remove battery, battery tray, strut tower brace, cold air intake and engine cover.

The majority of your header install will take place under the car, so the next step is to support the vehicle on jack stands or a car lift by the body. Do not support the car by the k-member, as partial removal of the k-member will be required for installation.

Once the car is safely in the air, remove the factory h-pipe.

Your next step is to support the engine.

We had access to these Ford engine lift hooks, and engine support. If you don't have access to these tools, I've supported the engine on similar header swaps by the harmonic balancer or with an engine hoist.

With engine carefully supported, disconnect the motor mounts from k member, disconnect the steering shaft, and disconnect the plug to the EPAS module on the steering rack. Then, unbolt the k-member and lower the rear of the k-member. We took the time to mark the k-member's position with a felt marker to insure it was reinstalled in the same position. Again, our tranny was out for our swap, so it looks a little emptier in there. Removal of the starter may also be required during this step. It's not necessary to completely remove the k-member. Unbolting it and lowering it down at the rear is sufficient enough to gain access to the headers.

Reinstall the Stainless Works headers using factory hardware and gaskets.

Reinstall your motor mounts, jack the k-member back into place, connect steering rack, and steering shaft. Install the Stainless Works x-pipe or extension pipes. Once the car is back on the ground, reinstall the battery, engine cover, cold air intake and strut tower brace. Once this is all done, check for exhaust leaks, load your custom tune, and have fun with your added power and sound.