Porsche 991 Carrera Product Development by Agency Power

The new Porsche 991 is more then just a body change for the 911 series.  Leaked out over a year ago, the 991 by Porsche was to completely change the way the 911 would be driven and open up a future to its progressiveness.  Over the years, and including my ownership of a 996 Carrera, 996 Turbo, 997.1 Turbo, and now 997.2 Turbo S, we have seen each model slightly get more and more refined.  The 991 wheelbase has increased 100mm over the outgoing 997 model.  As well, its overall length has also increased by 70mm.  A new transaxel was developed so that the rear wheels could be moved 76mm backward in relation to the position of the engine.  This significantly improved the weight distribution and cornering performance of the new 911.

Vivid Racing was able to get its hands on a 2013 Porsche 991 Carrera S to do product development with sister company, Agency Power.  The white color and beige interior are a nice combo with the 7 speed PDK transmission.  Instantly noticed is the rear end with the sleeker looking taillights and the decklid.  Curousity had me popping the decklid right away only to find a small 30 by 8 inch space with 2 fans and a logo.  (On a side note, for those that are wondering where the intake is or how to change the air filters, you can see our complete dissassembly of the rear end on the Project 991 Carrera Gallery Here.)  This should be fun I thought!  The front end has some more curves and the 997 lights are slightly carried over.  But the big in your face change is the inside.  The mini me center console of the Panamera is a big change.  Buttons are everywhere.  Having a PDK on my Turbo S, I was used to that and the function.  Turn the key on, the dash takes on all sorts of new LCD displays.  After learning where the newly positioned buttons were, we headed to the lift.

Like many OEM’s taking cue from the aftermarket, the stock exhaust is fitted with almost a valvetronic type setup which opens a flapper valve on the center muffler when the sport button is pressed.  However for the Porsche enthusiast, the vehicle is still lacking a true sports car noise.  Agency Power set out to build a modular exhaust system that would allow fitment for many different types of 991 drivers.  The exhaust is broken down into 3 parts:  The headers, the secondary mufflers, and the main center muffler.

The first part we built were the Secondary Muffler Bypass Pipes.  These simple U/J pipes remove the mufflers that are tucked up in the rear quarter panels.  Why the reason for these I do not know.  Typically in the past we either see a main center muffler or 2 mufflers with catpipes.  So this was the first simplest part to change out.  Keeping the same diameter for a perfect OEM replacement, these pipes are straight through which not only eliminates any muffler packing or baffling, but also the weight.  Each stock muffler weighs approximately 15.6lbs.  The Agency Power Muffler Bypass Pipes are about 3lbs each.  Now eliminating restriction, we have also saved about 25lbs off the rear end.  Because this part still retained the factory headers with cats and the factory center muffler, it added a slightly deeper tone to the exhaust but not a drastic droning change that a full exhaust could.  Upon revving the car out stationary and on the dyno, you could hear the tone change nicely as you past the 4000rpm mark.

According to our dyno test, the secondary muffler bypass pipes really start achieving performance from 3700rpm all the way to redline.  With a baseline test in 3rd gear and all wheel drive (have to for the dyno and no warning lights), the car made 344HP and 289ft/lbs of torque.  Based on the ambient temperature, the Mustang Dyno, and 91octane fuel, this is about right considering the car comes with 400bhp.  With the addition of our pipes, the car put down 358HP and 298ft/lbs of torque gaining 14HP and 9ft/lbs at the peak.  As you can see from the dyno plot, gains were higher and lower throughout the curve but always better then stock.

Contact us for pricing as these parts are available.  Stay tuned for our next update which is involves High Flow Cat Equal Length Headers!  You can also view other Porsche 991 Carrera Parts Here.

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8 Responses to “Porsche 991 Carrera Product Development by Agency Power”

  1. Dan says:

    Our next development project for the Porsche 991 Carrera is the high flow race headers. These headers are a big change in design compared to stock which now feature a 3 into 1 merge collector on either bank. The all stainless steel headers have an equal length design to improve the flow from the engine. Available in both catless and 200 cell high flow cats, we tested the more common version people will use with cats. To keep our modular focus, these headers are a direct OEM replacement. They allow you to run the stock main muffler and secondary mufflers or use our secondary bypass pipes.

    Our two objectives for this product were to gain power and have no check engine light issues. To avoid the dreaded CEL, we actually put a O2 spacer on the secondary O2 to raise it up out of the stream so it would not read the change from the high flow cats compared to stock. Under an extensive period of time driving on the dyno like one would on the street, the car still never threw any CELs for us. So having a baseline of the car stock with around 342.8hp, we gave these bad boys a run.

    An immediate difference was the sound. These headers really enhanced the sound of the 3.8L DFI engine. It was very GT3 sounding. When lifting off the throttle, it gave a little bit of back rumble. Without knowing the numbers, the dyno runs could be audibly and noticeably felt smoother through the RPMs. Once we finished our 3 runs, we looked at the graph and were quite amazed. Stock, the car has a very lumpy power curve. With our special 3 to 1 merge collector and equal length tube design, the power band became extremely linear and consistent with no hesitation or issues. In some areas of the curve it gained 30ft/lbs of torque! The Agency Power 991 Carrera Headers gained a peak of 11HP and 12ft/lbs of torque.

    If I had to make a choice on which to buy first, exhaust or headers, I would choose headers for the Porsche 991. Check out the video and pics below!

  2. Dan says:

    We took both of our new Porsche 991 products and ran them installed on the car compared to stock. This included the 200cell high flow cat race headers and 2nd muffler bypass pipes. Combined, the increase was mainly in the torque giving the car about 14hp and 14ft/lbs gain over stock. The best part about the combined parts is the newly enhanced GT3’ish sound that the 991 now gives off. Here is the video with dyno sheet and photos of the parts installed. These are now available for ordering.

  3. Dan says:

    991 is back in the building! We are going to be finishing the design of the center muffler to go with the rest of our modular parts. This will be an XPipe design. After the X design kit, we will also be doing a valvetronic setup for those that want LOUD! In addition, we also have the factory sport exhaust here which features its own X design. So we are going to do a dyno test to compare how that exhaust performs compare to the other stock box style system.

    While the exhaust is being welded up, we started to dive into our intake project. Rather then reuse other parts, we are going to develop a complete functional true cold air product that will retain the factory decklid air scoops. So here are some photos of what the car looks like with out the intake and the space you really have to work with!

    While we have the car here we did decide to do factory wheels in gloss black and a 20% tint for him. We are also adding the H&R springs so stay tuned for more updates and picture pics!

  4. Dan says:

    Continuing on our path of Performance Modularity for the Porsche 991 Carrera, we just finished up testing of our new center muffler X-Pipe exhaust. Like our headers and 2nd Muffler Bypass Pipes, this exhaust also fits with the stock parts. The factory center muffler has a 3rd chamber that opens up when you press the sport button and pushes exhaust gas, by passing the muffler. With the Agency Power center muffler, we incorporate a separate exhaust pipe that comes off near the X design and exits the floating tip. We tested the center pipe in conjunction with each stock part to hear the difference in sound and see the change in power.

    The first test was with the stock parts and the center X-Pipe exhaust. The baseline of the car has a very waivy ride through the RPM band. Whether conducted in sport or regular mode, this did not change. So we chose to run our tests in sport mode. From 3000rpm to 6400rpm the car made consistant power. From 3800-4200rpm the car made about 50hp and 80ft/lbs of torque! The rest of the curve yielded about a 20hp gain until it ran out of steam near redline. In regards to the sound, the XPipe alone made for a really crisp tone that could be tolerated and enjoyable for daily driving and wanting to get a more sportier feeling of the car. In addition to the great sound and power, the rear XPipe also saves about 20lbs off the rear end of the car.

    Our next test was with the 2nd muffler bypass pipes and the center Xpipe. Having already tested the 2nd pipes, we new that audibly, they only slighly changed the tone of the stock car. Paired with the x-pipe on the 991, this gave a slight increase to the exhausts pitch making it higher. Overall, this combination really only affected sound and weight as the power increases were the same.

    The final test was all 3 components together: Headers with cats, 2nd muffler bypass pipes, and center X-Pipe. When we tested the headers alone against the stock car, you could see how the special merge collector smoothed out the power curve all together. All the waiviness that the 991 Carrera would experience through the RPM was gone. With the collective efforts of all 3 parts, a smooth horsepower and torque graph became a reality. With a near 90ft/lbs of torque gain in the low end and a average gain of 40-50hp throughout the curve, this setup was definitely impressive. With power comes noise, and only those who want a exotic sound that makes heads turn should run this setup. As you go through the gears, the car unleashes a menacing roar as if you were watching a GT Porsche Cup race.

    Enjoy the pics and videos!

  5. Dan says:

    http://www.agency-power.com set out to add to its already strong horsepower proven exhaust components for the new Porsche 991 Carrera. Our next performance product is this cold air intake box. Prototype seen, the cold air intake box retains the factory air scoops that directly plum air into the voluminous airbox which features an enhanced air intake tube to the throttlebody with a massive K&N air filter which greatly improves airflow over the stock system. Since air intakes are designed to suck in air from the aerodynamics of the vehicle in motion, we tested the intake kit on a Mustang dyno utilizing high powered fans to simulate air going through the decklid scoops and into the box. Watch the video to see what the results were and stay tuned for pricing and finished product!

  6. […] products did very well on our dyno tests.  Independently testing each part as seen on our 991 Product Development page, cumulatively these performance parts take the 991 Carrera S into and past stock 997 Turbo […]

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