MAC PRO CHAMBER

I have the MAC Pro Chamber and cat back kit with Flowpath mufflers. It sounds deep and throaty. It has the classic Amercian muscle car sound. Not high pitched raspy sound that is typical of X-pipes with straight through mufflers. The box H-pipe and chambered mufflers produce more of a throaty sound.

The Pro Chamber I got is the three-piece design with the black high temperature sealant coating. It came with a metal sleeve for the drivers side connection to the exhaust manifold, and a cheap cardboard-looking gasket for the passenger side exhaust manifold connection. I read thread after thread on message boards about installing the Pro Chamber before hand. I made sure I had all the additional parts on hand before starting the installation. I picked up a pair of O2 sensor wire extensions, a Ford OEM gasket and the NAPA 600-1819 Exhaust Manifold Stud Kit.

To remove the factory H-pipe, start by disconnecting the H-pipe from the exhaust manifold. If you disconnect the factory H-pipe from the cat-back before the manifold, you'll need to support the H-pipe to avoid unecessary pressure on the exhaust manifold bolts. Be mindful of the four O2 sensors and their wires as you go along. Disconnect the sensor wires at the plug or remove the sensors from the pipe, depending on which sensor you are working with.

When installing the Pro Chamber, attach the Pro Chamber legs to the exhaust manifolds first. Fully tighten the manifold bolts. The three-piece design of the Pro Chamber makes it easy to work with the exhaust manifold bolts without the weight and pressure of the entire H-pipe. The primary O2 sensors should have no problem reaching the bungs on the legs.

Many people experienced troubles with leaks on the drivers side connection between the Pro Chamber and the exhaust manifold. The shoulder on the studs bottoms out before a good seal is made (see photo below). Some people resort to grinding off the shoulder on the factory studs. One solution I read is to replace the factory studs with the NAPA Stud Kit. Later Pro Chamber kits (including mine) came with a metal sleeve insert to address this problem. This sleeve goes into the Pro Chamber side of that connection and forms a good seal without having to modify or replace the factory studs.

The passenger side isn't known for leaks but it is a pain in the ass to reach. The pictures below will give you an idea how tight it is. The starter and the factory cat are in the way. It's not impossible to reach but you will need a 15mm medium to deep socket, a swivel joint and about two feet of socket wrench extensions. It turned out we didn't have any problems with these bolts like other people have reported. My car was only 11 months old when I did this mod. If your car is a few years old, the nuts could be hard to remove. A good shot of pentrating lubricant (like PB Blaster) should help out.

Another thing I kept reading about was the crappy Mac gasket (pictured earlier) for the mating surface between the passenger side leg and the exhaust manifold. The Ford OEM gasket is 100x better than the Mac gasket. There is an indentation on the exhaust manifold mating surface for the OEM gasket to sit in. The gasket is a little thicker than the indentation and will be compressed when the two mating surfaces are pulled together by the bolts. The MAC gasket will not fill the seat.

After getting the legs attached to the exhaust manifold, loosely install the chamber. The connection from the legs to the chamber and from the chamber to the flow tubes are really simple. There are two nuts on each side and no gaskets are needed. Attach it to both the legs and then the flow tubes. Hold the chamber in position and lightly tighten the nuts. Continue to adjust and align the chamber and the flow tubes as you tighten all the nuts. It is much easier to adjust and align things from the chamber back to the flow tubes than having to mess with the legs at the manifold end.

The O2 sensor wire extensions are needed for the secondary (rear) sensors on the 2004 models since the wires are shorter. These models have the rear O2 sensors located closer to the front, between the primary and secondary cats. On pre-2004 models, the rear O2 sensors are located behind the secondary cats and the sensor wire is longer. On the drivers side, we even had to cut the retaining clip that holds the sensor wire to a larger wire bundle to give it another inch or two in length. The photo of the factory H-pipe shows the front (green) and rear (blue) O2 sensors. I did not purchase a pair of the MIL Eliminators since I have the DiabloSport Predator. The Predator allows me to turn off the light and disable the rear O2 sensor tests. The default setting in the Performance Tune turns these off.

I love how the Pro Chamber sounds below 1700 RPM. It is a deep rumble. Almost like a Harley Davidson motorcycle. It speaks "I eat 4 bangers for breakfast". I also love how the Pro Chamber sounds above 2300 RPM. It is smooth and clean. You can almost visualize the exhaust pulses from each side moving in perfect synch. It is loud enough to be heard but still tame enough to be friendly on the street. The SOTP meter can really feel the car pulling harder all the way past 5000 RPM too. It is obvious that the Pro Chamber was tuned for 3000 RPM and higher. I'm not entirely thrilled with how it sounds around 2000 RPM under light to medium acceleration. There is a slight choppiness. Sort of raspy. It resonates inside the car. It was bad when the Pro Chamber was new. As time went on, it got less pronounce. Nevertheless, the growl above 2,500 RPM is just too sweet. The sound clips on MustangExhaust.com do no justice. The Pro Chamber sounds so much better while driving. A recording of reving the engine at idle doesn't really show it off. You have to hear it live to really hear it.

MAC CAT BACK

The Mac cat back uses the Mac Flowpath mufflers. These are chambered mufflers that give out a deep rumble. The cat back uses 2.5 inch Mandrel bent piping, which is a great improvement over the stock 2.25 inch pipes. The cat back was installed at a shop so I don't have any photos or installation notes to share. The car was only a month old at the time and I didn't spend the time to learn about the mod. I didn't want to screw anything up. Looking back, this would've been an easier thing to install than the Pro Chamber. It would mean cutting the stock pipes just above the rear axle, removing four bolts, then hanging and bolting in the new cat back.

The only thing I didn't like about the cat-back were the 2.5" tips. The stock tips on the Mustang GT are 3.0". The MAC 2.5" tips look weak in comparison. They didn't even line up with the bumper cutout. Both tips are closer to the center of the car. It felt like I was a cross-eyed kid. I took the car back to the shop for some adjustments but they claimed it was a problem with the cat back and that there was nothing more they could do. I disagree, but I'm not one to argue much. Fockers.

The 3.5" tips from MAC are around $200. If I ordered them with the original kit, it would have cost me a little over $100. The MAC tips go from just over the axle to the end that sticks out. That's a bit more than what I'd like to spend. No thanks. Instead, I bought some 12" aftermarket tips from Summit for $25 each. These are 3.5" rolled tips that look much like the stock tips on the Mach 1s and they fit the bumper cutouts much better. I had a muffler shop do all the cutting and welding.

The muffler shop adjusted the cat back a little and installed the tips. However, the tips were a little low and part of the cat back was knocking against the subframe under heavy acceleration. I took it back to the shop but they were busy. I ended up going to a different muffler shop for to get the tips pulled closer to the bumper so they fit better in the cutouts. The guy was a perfectionist and made sure the tips were centered. He also adjusted the pipes a bit so they are farther from the subframe. In the end, I think they look meaner than stock, yet refined.

Here are pictures of all three for comparison.

FACTORY 3.0" TIPS

MAC PERFORMANCE 2.5" TIPS

SUMMIT RACING 12" 3.5" TIPS

If there was one thing I could do different is that I would have ordered the 18" long 3.5" tips instead of the 12" ones. It would give a little cleaner look when viewed from certain angles. Look closely at the picture above. You can tell where the tips end. I don't plan on changing anything right now though. I still love how they look.

Final note:

I had the MAC cat back before the Pro Chamber and I have to say the cat back by itself gave off a deeper tone. It would easily set off car alarms. When the Pro Chamber was installed, the overall volume increased and the tone increase a little.

Cost:
$160.00, for the slightly used Pro Chamber
$15.00, for the OEM gasket
$35.00, for the O2 sensor extensions

$388.63, for the catback and installation
$54.85, for the new tips
$40.00, to put them on
$35.00, for the final touch

(Did any of this help? Leave some comments in the guest book. Let me know you were here.)