Swedespeed

For the Volvo Enthusiast

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19 June 2016

The Volvo enthusiast community is a small, close-knit group with many segments focusing on certain generations of vehicles. The second generation S/V60 platform, referred to as the P3 platform, has started to see more aftermarket tuning companies cater to this generation of Volvo vehicles. KPAX Performance engineered one of the first P3 cat-back systems for the S60/V60 T5 (five-cylinder) and S60/V60/XC60 T6 (six-cylinder). If you have been following us on Instagram, you know that for the past year I have been evaluating the KPAX GT6 system on my 2015.5 V60 R-Design. The KPAX exhaust offers a distinctive and aggressive exhaust tone while setting the foundation for future engine modifications.

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For this review, I wanted to live with the exhaust and evaluate how it held up for at least ten thousand miles and a couple winter seasons. Many swedespeed readers asked questions such as “is the system is too loud?” or “if a new rear valence is needed?” A new rear valence is not needed if you are comfortable adjusting exhaust hangers to get the appropriate clearance around the exhaust tips. Volume and tone of an exhaust is a very subjective. For example, the KPAX is noticeably different and louder than the quad tip HEICO system. The KPAX is more aggressive where as the HEICO has a deeper tone yet it sounds tame like the stock exhaust. Perhaps a more relevant question to ask is, “Will my significant other, who is not a car person, notice the exhaust?” I will be honest and say, your significant other will notice this exhaust, especially at cold startup. However, you can you still manage to sneak home after late night card game. You may find the urge to keep the RPMs above 3500 each time you drive through a tunnel or have an opportunity to echo the exhaust off concert walls. The KPAX GT6 bellows a mature and addictive sound that one does not expect from a Volvo. In fact, the team at KPAX used the V8 Maserati QP as their sound benchmark during development.

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The 2.75-inch (69.85mm) exhaust pipe is .25-inch (6.35mm) larger than the factory 2016 Polestar 2.5-inch (63.5mm) pipe. The entire system is made of T-304 austenitic stainless steel. The center resonator and rear muffler are both custom designed for the 3.0L T6 motor. After sixteen prototypes, the team arrived at the current setup. The prototypes included a number of 3-inch (76.2mm) exhausts but they did not yield any more power or torque gains. Since KPAX was very focused on a very unique sound, they decided to stick with the 2.75-inch (69.85mm) pipes to allow more freedom with the sound tuning. 

KPAX partnered with Borla Performance Industries, a thirty-year exhaust system pioneer and exhaust industry leader. Development and testing was conducted in Ventura, CA where Borla has their research and development facilities. The KPAX team spent nearly two months developing the GT6 exhaust system. Road and track testing was performed around the streets of Sonoma, CA near the KPAX headquarters. Sonoma Raceway and Thunderhill Raceway were their main high-performance testing venues. These facilities were also used to develop the KPAX handling, braking and GT packages for the rest of their product catalog. The KPAX system is manufactured in Tennessee with steel sourced from American foundries.

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The components:
The care and quality of the exhaust components started with the thorough packing. The pieces arrived well protected and in perfect condition. The pipes are mandrel bent with smooth curves for maximum efficiency. The welds are clean and precise. Being a bit obsessive compulsive, and preferring aftermarket products to be stealthy, I coated the rear muffler with a 1200-degree high temp paint, which has held up extremely well during the past year. I have tried 500-degree ceramic paint on a previous system and it cooked off, so if you are considering paint, prep the surface properly and get the very high temperature rated ceramic paint for durability.

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The Installation:
At the factory, Volvo installs the exhaust system as one long piece without separable joins. Ideally, if you have access to a lift, you can remove the system with a reciprocating saw making a single cut above the rear axle. This is the most difficult part of the KPAX installation. Using a set of Race Ramps (www.raceramps.com), I did not have enough ground clearance to twist the system out so I was forced to make a second cut. With the OEM exhaust removed, the KPAX fits into place perfectly. Getting the 4”(101mm) exhaust tips align is where you may spend most of your time. Keep the clamps in the system snug, not tight. Determine if the factory metal hangers align to your visual preference. I like to have about one finger width from the top of the pipe to the rear valance opening.

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Does it Make a Difference?
Another popular question is, “Does the exhaust make more power?” There are essentially two basic components, horsepower and torque, that owners discuss when comparing the power of one vehicle versus another. There are many excellent write-ups accessible via a Google search but essentially, horsepower is defined as 1HP is the equivalent of moving 33,000 pounds, one foot in one minute. There are three things accounted for in this measurement: the amount of weight involved, the distance its being moved, and how long it takes to do it. Torque is the measurement of twisting or rotational force. One measurement of this is pound-foot(lb-ft), the rotational “force” generated by hanging a one-pound weight at the end of a one-foot wrench.

There are many variables that affect horsepower and torque numbers and what is key for your project is to be consistent. Find a dynamometer and start with a baseline measurement and as you add modifications, measure against that baseline. The delta between your baseline and your new number is the power gain or loss. Variables such as air-fuel mixture, fuel quality, ambient temperature, humidity, settings on the dynamometer, and the type of dynamometer each contribute to the amount of power measured at the wheels. A Mustang dyno will have different numbers than a Dynojet. Your numbers may appear to be significantly lower or higher than your buddy with the same vehicle, same fuel, same mods, same ambient temperature, etc. It is important to be consistent, stick with the same dyno otherwise you will end up with an Apples to Oranges comparison. Let’s take a look at how my V60 measured.

Stock baseline: 269hp and 333 lb/ft.
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The V60 performed best with a 3rd gear pull. Using 4th gear took too long and the car was going 120mph on the dyno. The next, the V60 was measured with the KPAX exhaust installed. The dyno accounts for temperature differences and applies that variable to the calculation.

KPAX Exhaust: 270hp and 354 lb/ft.
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For the KPAX measurements we had an issue getting the dyno sensor properly secured to the coil pack but the dyno operator assured us the numbers were accurate. The calculated horsepower results were essentially flat but the torque number bumped up 21 lb-ft. The torque increase is felt in the mid-range when accelerating giving the V60 a more spirited experience.

The KPAX Performance exhaust system delivers an aggressive tone complimenting the 3.0L six-cylinder T6. The sound offers just enough without being over the top. Owners that have never had an aftermarket performance exhaust may find it too aggressive but if you are planning to maximize power output, this is the exhaust to get. The 4-inch tip is the perfect size to fill the rear valence openings. Overall, I am very pleased with the quality, the look, the sound and the dyno results. I look forward to building on these gains.

Check out the KPAX Performance Cars website to find a dealer near you.

Dyno: DynoJet 424x (awd)
Car: 2015.5 V60 R-Design AWD automatic

Additional results:

KPAX Performance Exhaust
270whp | 356 lb-ft
269whp | 342 lb-ft
268whp | 354 lb-ft

Stock Baseline
269whp | 333 lb-ft
268whp | 335 lb-ft

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