Project Subaru BRZ Gets Wheels, Performance Upgrades

Now that our project Subaru BRZ is handling and sitting properly, it’s time to give it wheels worthy of its good looks and a performance kick.

Before our staggered set of 18-inch Work Wheels VS-XX arrived from Japan, we took the Subaru BRZ, in stock form, to a local dyno in Southern California to gather baseline data. But in order to do that properly, we reached out to AEM Electronics for a Wideband Failsafe Gauge so that we could monitor our air-to-fuel ratio. Though we have no plans to try forced induction, the Wideband Failsafe Gauge is still an invaluable tool for determining how the modifications affect performance.

Playing it Safe on Engine Mods

Anyone planning to modify the engine in their FR-S or BRZ will appreciate the built-in “failsafe” found in the gauge.It serves as extra insurance toward protecting your motor. By constantly monitoring the air-to-fuel ratio on your vehicle, the gauge can activate a user-defined failsafe strategy if the vehicle runs too lean.

An internal data logger also allows you to easily pull information from the easy-to-install gauge. We bought an angled gauge mount ring and simply cut a hole in the factory passenger dash piece for the gauge installation. The additional O2 sensor was installed on the factory overpipe to monitor the air-to-fuel ratio.

With the vehicle completely stock and with the air-to-fuel gauge installed, we drove to the dyno for those figures. After letting the car cool down, we let it rip on the dyno where it pulled 160.30 hp and 137.57 lb-ft of torque straight out of the box. Accounting for a roughly 20 percent loss in the drivetrain, the output is right within the expected range.

The BRZ was then taken apart for exhaust modifications. First, we swapped out the factory overpipe and front pipe for a Motiv Concepts overpipe and high-flow catalytic converter (HFC). Using 2.5-inch diameter stainless steel exhaust tubing, both the overpipe and HFC will increase power while giving the BRZ a deeper exhaust tone. After the installation, we strapped the car back down on the dyno to see 164.92 hp and 139.03 lb-ft of torque at its peak. Power gains were made throughout the RPM band.

Those looking to get some extra performance out of their FR-S or BRZ without making their vehicle louder should consider an aftermarket overpipe or HFC setup. By maintaining a catalytic converter, the vehicle isn’t as loud as it would be by removing it, and it will still be legal in most states. We do, however, suggest checking your state laws before any exhaust modifications.

Cat-Back Exhaust, You’re Up

Next up, we decided to bolt-on a cat-back exhaust system from Motiv Concepts to give the BRZ a new exhaust note, hoping for performance gains along the way. By removing the factory resonated midpipe and installing the 2.5-inch midpipe and muffler section, the BRZ picked up a few more horsepower – now at 167.82 hp at its peak and 142.27 lb-ft of torque. Overall, more than 7 hp was gained from the exhaust modifications, and torque improved throughout the powerband, which is a weak point for the BRZ.

Finally, to complete our bolt-on modifications, we removed the factory air intake and installed a unit from AEM. The electronically tuned intake (ETI) system eliminates the need to detune the intake tube because it crosses the mass air flow (MAF) sensor. As a result, the intake tube sports a slightly larger diameter than the factory equipment without the threat of check engine light being triggered. The system features a sealed air box that uses polypropylene to shield the AEM Dryflow filter from heat under the hood. The MAF sensor is also moved into the custom air box and uses stock, fresh air pathways to feed the filter with colder, outside air.

The bolt-on system is easy to install and sports a factory fit and finish. Back on the dyno, we saw peak horsepower hit 172.79 hp while torque showed 140.27 lb-ft at its peak. It’s worth noting however that the dyno was missing data between 4,500 rpms to 5,000 rpms – we suspect that the intake increased torque at the peak, but unfortunately the dyno had a hiccup and missed the data. Just by looking at the graph, torque improved throughout the powerband, so we suspect a more accurate reading would be around 145 lb-ft of torque at the peak. Regardless, the intake made a vast improvement.

With the new AEM intake installed and the Motiv Concepts exhaust components, the BRZ sounds like a new machine. The large muffler design keeps the exhaust quiet in normal driving conditions, but on full throttle, it’s easy to hear the difference. The BRZ engine’s notorious torque dip is also noticeably improved, allowing the RPMs to climb faster under load.

Time for New Wheels and High-Performance Rubber

After our trip to the dyno, we were pleased to receive a phone call from Work Wheels USA to hear that our custom staggered set of 18-inch VS-XX wheels had arrived from Japan. While many 86 owners prefer lightweight 17-inch wheels, we opted for larger 18-inch wheels to give our BRZ a more aggressive stance without ruining the handling. The result was an 18×8.5-inch setup in the front with a +32 offset and a 18×9.5-inch setup in the rear with a +39 offset.

We decided to pair the matte bronze wheels to a set of Falken FK453 tires, 225/40/18 in the front and 255/40/18 in the rear. The FK453 is the latest in Falken’s generation of ultra-high performance tires and features a new silica compound for better dry and wet grip performance. The asymmetric tread design not only provides enhanced cornering performance for our BRZ but keeps tire noise at a minimal.

Having our new wheels and tires in hand, we returned to Wheel Warehouse in Anaheim, Calif. to have the factory tire pressure monitoring system (TPMS) transferred from the factory wheels. Now, the BRZ not only looks the part, but handles better thanks to the upgraded rubber.

Up next for our daily driver, we’ll address the BRZ’s factory stereo system. Yes, yes, we know, the BRZ wasn’t meant to sound great inside the cabin – who wouldn’t rather hear the exhaust note as you rev through the gears? But let’s face it, any vehicle that’s a daily commuter needs to sound reasonable inside. So for our next installation, we’ll take a look at a budget build that will transform the audio to something more acceptable.