Test Notes
Unlike other software tweakers that offer a base map only, Revo can further adjust fuel mixtures and ignition values to get the best out of your vehicle's current modifications through any of its nation-wide dealers. In fact, Revo encourages visiting a dealer, even after you've installed its software using the handheld module, to make sure your car is running optimally. Furthermore, throttle response can be fine-tuned to the owner's liking.

While this is good, we did even better by enlisted Revo's own George Osmun to fly out to Kansas City and give this Audi the personal treatment. After loading up a program he was happy with, the car netted a peak 13.5 hp and 11.6 lb-ft of torque in the middle of the rev range.

As with other software upgrades for drive-by-wire cars, the increased throttle response is obvious-actually, a little too responsive for me. Car owner Chris Smith, however, loves it. Either way, Revo can fine tune it to the owner's liking.

The increased revs from 8100 to 8300 rpm are also quite noticeable, helping acceleration times in the lower gears.

Test 2
Peak power: 336 hp @ 7500 rpm
Peak torque: 276 lb-ft @ 3400 rpm
Max power gain: 10.2 hp @ 7500 rpm
Max torque gain: 7.0 lb-ft @ 7500 rpm
3000-8000 rpm acceleration: 8.07 sec.
Temperature: 79° F
Humidity: 16%

Parts: K&N drop-in filter
Installation time: 30 minutes
MSRP: $50

• Slight increase in power
• Slight increase in fuel economy
• Easy installation

• None

Test Notes
Decent bang for your buck, the K&N filter is not bad. It's also impressive that the car improved by an additional tenth of a second on the dyno pull despite the warmer weather. Unlike conical intake systems, there is no increase in sound volume by installing this filter-simply power gains and most likely a little better fuel economy.

With the K&N filter and Revo Stage 1 software installed we're already up to a peak gain of 17 hp at 6700 rpm and 16.1 lb-ft at 5000 rpm. Not bad for $750 and a little over an hour of installation time.

Test 3
Peak power: 335 hp @ 7500 rpm
Peak torque: 286 lb-ft @ 3600 rpm
Max power gain: 8.6 hp @ 3600 rpm
Max torque gain: 12.5 lb-ft @ 3600 rpm
3000-8000 rpm acceleration: 8.01 sec
Temperature: 80° F
Humidity: 19%

Parts: Magnaflow cat-back exhaust system
Installation time: 1.5 hours
MSRP: $1,228

• Good fit and finish
• Great sounds
• More than 20 pounds of weight savings

• Needs properly tuned ECU for performance gain

Test Notes
Magnaflow's stainless steel exhaust system is comprised of 2.5-inch tubing, and includes a "Tru-X" exhaust pipe, dual rear mufflers and quad 3-inch double-wall tips. On start-up the new V8 tone makes its presence known, sounding much deeper than you'd think a 4.2-liter V8 would. On the dyno, our first several runs netted us torque gains low in the range but a 10-hp loss up top.

After repeated runs with the engine properly warmed up, our best run netted 326 total whp. It didn't make sense until we noticed the curve hit south right after 4000 rpm, then realizing the difference in the air-to-fuel ratios. Although the Revo software was there, it doesn't affect the factory ECU's adaptive parameters, which apparently compensated for the exhaust's initial extra flow with what was apparently too rich a fuel mixture. In fact, it nearly dropped a full point, from 13:1 to 12:1.

With Revo's George Osmun still by our side, he gave the software one click to lean out the fuel mixture across the board one notch, and the power immediately returned. We still didn't net a single horse from 4000 rpm on from the exhaust system-even after the software adjustment-but the car netted a respectable 8.6 hp and 12.5 lb-ft at 3600 rpm. While this won't help in a drag race, it definitely peps up daily commutes, highway passing, and powering out of slow speed turns.

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