It is winter, and Project GT3 sleeps soundly in my heated garage, quietly pining for spring. Such a shame, not to be able to drive it. Hearing the glorious sound of its motorsport-inspired 3.8-liter flat-six, feeling the continuous thrust blasting down the front straight, well into the triple digits, at my home track, or interpreting the miraculous chassis feedback through the grippy steering wheel and tight-fitting bucket seats in any given corner. What to do? Well, it’s best to do something other than daydream the hours away. So, like other European car enthusiasts stuck in the Snow Belt, I needed to conceive, plan and execute a new modification to keep me up close and personal with my four-wheeled pride and joy during this downtime.
Actually, it’s rather difficult to come up with a viable modification on a Porsche GT3 that is destined to pay dividends in both pure enjoyment and improved performance; it’s as perfect a sports car that can be had from the factory floor. However, after a trip to Slovenia last summer to visit Akrapovic, manufacturer of full titanium performance exhaust systems (“Titanium Revolution,” May ’11), my plan was simple. I would install a full titanium exhaust system on the GT3. With this addition I’d definitely be losing some weight, hopefully freeing up some power, and possibly improving the car’s handling, all in one giant leap.
I selected the Akrapovic Full Evolution system (headers, race cats, side and rear mufflers and tips). This setup works as precisely as the OEM system, utilizing the same three-muffler configuration; it allows exhaust flow through both the side mufflers and rear muffler, or just the rear alone when activated by the ECU or “Sport” button. Note that Akrapovic also offers three other GT3 system configurations to choose from.
At the factory I was able to see first-hand the quality, engineering and artistry that goes into each and every Akrapovic product, but for retail consumers their first impression forms when they begin opening the boxes. If you think the packaging is upscale, well wait until you see what’s inside. It is a sight to behold; displaying it in a gallery might seem more fitting than bolting it underneath your car. But we won’t be hanging these lightweight bits on a wall—let’s do the install, and see the benefits with some thorough dyno testing.
I began with some baseline dyno runs at my local shop: RCTS Canada R&D in Calgary, Alberta. They graciously volunteered their time and their 248C Dynojet for our power testing. All runs described in this article were done with the same climate-controlled dyno, the same operator, the same gear (Fourth), the same fuel (Shell 91), the same brand-new dyno-dedicated air-filter, the same rear brake setup (Stoptech Trophy STR, 355mm two-piece rotors), the same 19-inch wheel-and-tire setup (Forgeline ZX3-S centerlocks and Toyo R888s), the same air pressure in the rear tires (36 psi) and with “Sport” mode activated.
The installation is fairly straightforward and the supplied step-by-step instructions are excellent, but as usual you’ll need time, patience and good mechanical aptitude to accomplish the task (see the sidebar for a quick description). Akrapovic supplies ample sealant and thread anti-seize paste, but no new header gaskets came with the system. The original gaskets can be reused in a pinch, but I highly recommend using a new set. I ordered some in advance, at a great price, from SunCoast Porsche.
After the install was complete, the final fit and finish can be described as near perfect. I have a very minor issue with the rear muffler and heat shielding rubbing on the right side of the lower bumper shell edge, but this may be specific to my car since Akrapovic has had no other incidence log of such a problem. One final note: The manufacturer weight savings claim for this exhaust system is a substantial 17 kg (37.5 pounds) off the rear of the car; this was fully confirmed to within less than a pound when I borrowed my wife’s kitchen scales. (Don’t tell!)
Once the exhaust was in place, it was run in for a week or two when the snow finally melted, and then it was back to the RCTS dyno for the big test. The best of three dyno runs demonstrated solid results, with peak values of 383.6 whp and 274.4 lb-ft of torque, up a significant 13.3 whp and 9.9 lb-ft; this was equivalent to the manufacturer’s claim within a reasonable scientific error. So the Akrapovic Full Evolution exhaust system truly makes power. The graph shows the Sport mode comparison with the baseline run plotted in blue and the final dyno run in red. These results show a healthy curve with 10-13 whp and 15-30 lb-ft gains on the low end, a minor dip in power and torque from 2950 to 4300 rpm (not as pronounced in “Normal,” i.e., non-Sport, mode), and excellent 10-20 whp and 10-15 lb-ft gains upwards to the 8500-rpm redline. Be aware that the results are likely to be even better when the vehicle is run on the street or track with full cooling and airflow.
The added power is certainly noticeable from the seat of the pants, and most welcome. However, the deeper, much more mechanical and racy soundtrack, and the amazing weight savings is what slams home the true value of this system’s high price of admission (MSRP $12,495). Where the stock GT3 exhaust note is civilized and muted by comparison, the Akrapovic Full Evolution system allows the full motorsport bandwidth of the GT3’s flat-six to blow through the spectacular upsized titanium exhaust tips. In Normal mode below 4200 rpm all three mufflers are utilized, so your neighbors aren’t going to be too upset with you. But pressing the Sport button, you can choose to cause audio mayhem, depending on how much right foot is applied. Thus, the new system gives a true Jekyll-and-Hyde effect—it can be borderline conservative, or just plain wild and nasty.
One minor downside to this installation is the occurrence of an engine check light signaling the malfunction codes for inefficient catalytic converters on both cylinder banks. Such is the price of replacing the OEM cats with the power-enhancing 100-CPI race units. A software remap for the ECU is the only remedy for this issue. Akrapovic is currently making corporate alliances with performance software vendors to help streamline solutions for their customers.
Next time, we’ll get back on track with our GPS lap testing and add some suspension tricks to tweak the already excellent handling.
First, remove the rear bumper shell and inner bumper heat shielding on both sides. Then, remove the aluminum bumper and additional heat shield off the rear of the car. Next, the rear muffler can be unbolted by first loosening the plates on each side. All four O2 sensors are then removed from the exhaust piping and tucked out of the way, leaving them wired up. Working on each side, remove both side mufflers and associated bypass pipes, then release the rear muffler by removing the mounting straps. Finally, unbolt each header/cat assembly from the engine block. The install is the reverse of this process; be sure to use plenty of sealant and thread anti-seize paste per Akrapovic’s instructions. Note that you will have to reroute the O2 sensor wiring slightly. —DN