• Hot coolant from the turbocharger is not fed into the overflow bottle; instead it goes back into the system to (eliminates the possibility of melting the overflow bottle)

• O2 sensor heat sinks reduce risk of damage to sensors from excess heat

• Initial cost of investment; upgrading to this level of power requires additional upgrades (clutch, suspension) and a good set of tires

Test Notes
Because of the lengthy installation time involved and schedule conflicts, this test was performed one week after the baseline test. The GIAC software increased the rpm limiter to 7200, allowing the engine and turbocharger to produce power outside of the factory rpm range. So when we quote max power gains, we quote the gains within the factory rpm range and with the new rpm range from the software.

Milltek Cat-back Exhaust
With milltek high-flow catalytic converters
Test 2
Peak power: 347 hp @ 5900 rpm
Peak torque: 335 lb-ft @ 5000 rpm
Max power gain: 28 hp @ 5400 rpm
Max torque gain: 27 lb-ft @ 3400 rpm
Temperature: 82° F
Humidity: 30%

Parts: High-flow catalyst assembly, exhaust sealant, clamps, resonated front pipe section, rear silencer w/100mm tips, Milltek stickers Tools: 13mm and 16mm socket, pry bar, ratchet, anti-seize, 22mm box wrench, WD-40 Installation time: 1-1.5 hours MSRP: $2,498

• Mandrel bent tubing stainless steel piping
• Reduced weight when compared to the stock system
• High quality catalytic converters reduce backpressure and optimize flow while keeping emissions in check to prevent check engine light
• Exhaust can be purchased with or without a resonator on the front pipe to control sound levels

• Slip-joint construction requires a few attempts to get everything lined up
• Once muffler clamps are tightened, system is difficult to remove or adjust

Test Notes
We had to let the exhaust cool for a while before we swapped it out. By the time we were finished it was time to call it a day, so the exhaust test was performed the following morning.

VF Engineering RSs-32
Race gas vp-109 software and fuel pump
Test 3
Peak power: 407 hp @ 6700 rpm
Peak torque: 375 lb-ft @ 3800 rpm
Peak gain: 83 hp @ 6900 rpm
Peak gain: 60 lb-ft @ 3500 rpm
Temperature: 69° F
Humidity: 30%

Parts: Software, fuel pump
Installation time: 1-1.5 hours
MSRP: $1,400

• GIAC multi-program option allows easy switching between 91 and 109 octane
• Great way to get extra power for a day at the track or an excursion through the canyons

• Cost of VP-109

Test Notes
After we ran the Milltek exhaust dyno, a quick glance at the vehicle's fuel gauge told us that there was too much fuel to accurately run the VP-109 fuel test. We could have drained the fuel tank but instead the vehicle was driven until the fuel tank was nearly dry, which took a few days. Once it was dry and the parts and software were installed, we added two gallons of the VP-109 and ran the test. From beginning to end this Proven took about two weeks to complete, not normally the way we like to do tests, but that's just the way it had to be. We should point out that during this test there was a 13 degree drop in outside temperature-a definite advantage for a turbocharged engines and enough to give a more positive result.

Conclusion The MKIV R32 test vehicle was in near stock form with just suspension modifications including Bilstein PSS9 coilovers and front and rear swaybars. After I did the baseline runs, I dropped it off at VF engineering for turbo installation. Three days later I came back to do the second round of dynos with just RSS-32 turbocharger system installed. The numbers were impressive and the dyno plots were pretty smooth - always a good sign. After multiple runs to verify the results, it was time to get off the dyno and onto the road.

Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!