2007 Audi A4 Quattro Tiptronic - European Car Magazine

Our little 2.0T Tiptronic Quattro is back. Our testing began a few years ago with APR software and a Carbonio intake netting us 60 wheel horsepower in the midrange and even greater torque, and peak power went from 146 whp to 195 whp (Proven, July ’07). Shortly after, the factory plastic bypass valve took a dive and we replaced it with a Forge Motorsport aluminum unit.

A couple of years later an AWE intercooler and Okada Projects coils were installed, giving the car better spool-up, the much cooler air intake temps culminating in over 200 whp through the stock exhaust (Proven, March ’09).

Twenty thousand miles later and the car’s performing well, but the owner is thirsty for more. Since turbocharged engines usually net decent gains from a free-flowing exhaust we enlisted the help of Stasis Engineering and RAI Motorsport. When the parts arrived we took them to our friends at Modified by KC, who we use for lots of our dyno testing and installations.

Fluid and air temperatures were monitored using our Actron Elite AutoScanner Pro CP9185 for accuracy and repeatable results, and to ensure our ignition system was up to par we installed a fresh set of NGK BKRE7IX spark plugs we ordered from Sparkplugs.com.

Vehicle Data

Engine: 2.0-liter I4, FSI, turbocharged
Transmission: Six-speed Tiptronic
Mileage: 42,300
Current modifications: APR software, Carbonio intake, Forge Motorsport bypass valve, Okada Projects ignition coils, AWE Intercooler

Dyno data
Dyno type: Dynojet 424x
Temperature: 67-89 F
Humidity: 21-52%
Test gear: Third

Performance
Peak Power: 195.2 @ 5000 rpm
Peak Torque: 236.4 lb-ft @ 3800 rpm
2200-6500 rpm dyno accel: 13.4 sec.
Temperature: 89 F
Humidity: 21%

Test Notes
We left the AWE Intercooler test with a peak 203 whp. With so much time between then and now, a new baseline was in order, which made our starting point today 195 whpa little down from last time, but a quick compression check showed near-perfect results, putting our mind at ease. When testing parts, it’s not the peak baseline power that matters, but what the improvement is over baseline that matters most, and we were glad to have a smooth start.

Stasis Engineering
Cat-back exhaust system

Test 1

Performance
Peak Power: 202 hp @ 5000 rpm
Peak Torque: 246 lb-ft @ 3600 rpm
Max HP gain: 13.0 @ 3400 rpm
Max TQ gain: 20.9 lb-ft @ 3200 rpm
2200-6500 rpm dyno accel: 12.78 sec.

Temperature: 87 F
Humidity: 21%

Parts: Stasis Engineering cat-back exhaust system
MSRP: $1,195
Installation time: 1 hour

Pros

Cons

Test Notes
After removing the factory cat-back, with its odd crimps, less subtle bends and smaller-diameter tubing, we knew there were gains to be had. The dyno confirmed it with an improved spool-up by a whopping 250 rpm, and an average gain of 20 lb-ft of torque from 3000-3400 rpm. This translated into a three-quarter-second quicker acceleration test.

Power-wise, there’s a consistent gain from 3700 rpm and up, averaging about 6 whp throughout the rest of the rev band. The icing on the cake is a weight savings of over 20 pounds and a slightly deeper and mellower exhaust tone that sounds pleasantly refined. It’s deep, but not loud, nor does it drone.

It should be noted that even though the ambient temperature and humidity were nearly identical to the baseline run, the dyno’s correction factor still took out an additional one percent in power over our baseline. We left it alone, but we think we may have been robbed of a couple of ponies by the dyno’s correction software.

RAI Motorsport
Downpipe and catalytic converter

Test 2

Performance
Peak Power: 205.2 hp @ 5000 rpm
Peak Torque: 264.5 lb-ft @ 3600 rpm
Max HP gain: 15.0 hp @ 4300 rpm
Max TQ gain: 21.2 lb-ft @ 3700 rpm
2200-6500 rpm dyno accel: 11.97 sec.

Temperature: 67 F
Humidity: 52%

Parts: RAI Motorsport downpipe and catalytic converter
MSRP: $650
Installation time: 4 hours

Pros

Test Notes
Installing the RAI downpipe is fine, but removing the factory downpipe is a near nightmare. Fortunately, the guys at MKC were up to the task. The new RAI downpipe fits beautifully, with only tightening the hard-to-reach V-band clamp being the extra 10-minute challenge.

With the new downpipe installed it was as if we’d duplicated the gains we got from the cat-back. Another three-quarters of a second was shaved from our dyno acceleration time thanks to another jolt in turbo spool-up, only this time the top end wasn’t as positively affected. The small factory turbo is the easy culpritit’s simply running out of lungs at high rpm, dropping boost pressure significantly.

The 300-cell catalytic converter, while much freer-flowing than the choked stock unit, helps keep the exhaust noise in check while freeing up gobs of torque.

During those few hours it took to install all the parts, the temperature outside literally dropped over 30 degrees F, and it hailed. So while we couldn’t duplicate the exact ambient temperature inside the dyno room, the coolant and intake air temps were kept within a few degrees so that our ignition timing was the same, which we verified. That said, the dyno’s correction factor still took out an additional two percent compared to the previous runs.

One thing we did notice is while in our cat-back test the air/fuel ratios didn’t change and maintained AFRs at mid-11s up top, the addition of the RAI downpipe richened the mixture to an upper 10, and the brunt of the difference happens from 5000 rpm-on.

Conclusion
For chipped 2.0T FSI cars, these exhaust upgrades are perfect. Aside from shelling out some coin, it’s as if they have absolutely no drawback. While the exhaust is slightly louder and noticeably deeper in a refined sort of way, the power gains are significant. The new exhaust tips provide a distinct aesthetic improvement and the whole system shaves 30 pounds of weight, while adding 10 whp at high rpm.

The best part is the full exhaust was good for a whopping 500 rpm improvement in spool, translating to a peak gain of 26 whp and 42 lb-ft of torque at 3300 rpm. On the dyno, this showed as a 1.4-second improvement from 2000 to 6500 rpm in Third gear, most of which happens between 2000-4000 rpmright where the majority of owners will feel it most often. Needless to say, to this owner the A4 feels like a new car again, and he’s ecstatic. We’d just like to see a bigger turbo that the transmission can withstand as a future upgrade.

Special thanks to Modified by KC for their continued help with our testing and installs. All wheel-horsepower figures were actually all-wheel-horsepower figures, which usually net around 10 to 15 percent lower numbers than in two-wheel-drive mode. In addition, automatic-transmission equipped cars usually tend to yield lower numbers than manual-transmission cars.

Costs Summary

Exhaust
$1,195

Downpipe and cat
$650

MSRP Total
$1,845