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.