Super Street Network

Due to the EU’s Global Data Protection Regulation, our website is currently unavailable to visitors from most European countries. We apologize for this inconvenience and encourage you to visit for the latest on new cars, car reviews and news, concept cars and auto show coverage, awards and much more.MOTORTREND.COM
 |   |   |  Audi RS4 GruppeM Intake VS. K&N Drop-In - Proven
Subscribe to the Free

Audi RS4 GruppeM Intake VS. K&N Drop-In - Proven

Will GruppeM's "Ram Air" system make more power than the K&N drop-in?

Pablo Mazlumian
Mar 24, 2011

You may recognize this car--we tested a K&N drop-in filter, MagnaFlow exhaust, Stratmosphere downpipes sporting high-flow cats and Revo software on it once before. With those mods power jumped from 321 whp to 341 whp (Feb. ’10).

Epcp_1104_01_o+audi_rs4_gruppem_intake_vs_k_and_n_drop_in+audi_rs4 Photo 2/13   |   Audi RS4 GruppeM Intake VS. K&N Drop-In - Proven

Since then, the car’s been running great but the owner’s been thirsty for more. With only one aftermarket RS4 intake system available that we know of, we ordered a GruppeM Ram Air system from Modified by KC. Whether it would make any more power than the K&N drop-in we didn’t know (we didn’t think so), but we were curious enough to try. The trick with dyno testing an RS4 is in monitoring fluid, ambient and intake air temperatures, which have to be the consistent from run to run. This allows the ECU to trigger the same, and optimal, ignition timing and fuel mixtures. We monitored these parameters using an Actron Elite AutoScanner Pro CP9185 scan tool. Our scanner was also used to monitor temperatures during our 60-120mph pulls, ensuring accuracy, and the times were recorded using the GPS-based PerformanceBox from VBox USA.

Vehicle Data

Epcp_1104_03_o+audi_RS4_gruppem_intake_vs_k_and_n_drop_in+filter Photo 3/13   |   Audi RS4 GruppeM Intake VS. K&N Drop-In - Proven

Engine: 4.2-liter V8 FSI
Transmission: Six-speed manual
Mileage: 16,450
Current Modifications: Milltek/Stratmosphere downpipes, MagnaFlow cat-back exhaust, Revo Technik Stage 2 software, Continental ContiSportContact 3 tires, Forgestar F05 wheels
Dyno Data: Dynojet 424x
Temperature: 75-82 F
Humidity: 10-16%
Test gear: Third

Peak power: 341.9 hp @ 7500 rpm
Peak torque: 296.7 lb-ft @ 3800 rpm
3000-8400 rpm dyno acceleration: 8.74 sec.
Temperature: 75 F
Humidity: 16%

Test Notes
To retest the K&N with the car’s current mods, we returned the intake back to its stock paper element for a new baseline. Like other newer cars, the RS4 goes through a lot of ECU adaptation on the dyno. With similar temps, the runs started off in the upper 320 whp range and finally reached the 340 range consistently, but not until after 10-12 runs. We knew we’d have to give several runs and about an hour’s worth of pulls for each upgrade when taking cool-down time into consideration.

Epcp_1104_04_o+audi_RS4_gruppem_intake_vs_k_and_n_drop_in+audi_RS4 Photo 4/13   |   Audi RS4 GruppeM Intake VS. K&N Drop-In - Proven

This was the highest number we got so we went with it as our baseline. We were surprised to see almost the same horsepower we left off with from over a year ago, when we also had a K&N drop-in filter installed.

K&N Drop-in Filter

Epcp_1104_02_o+audi_rs4_gruppem_intake_vs_k_and_n_drop_in+k_and_n_drop_in_filter_test Photo 5/13   |   Audi RS4 GruppeM Intake VS. K&N Drop-In - Proven

Test 1

Peak power: 352.7 hp @ 7200 rpm
Peak torque: 303.2 lb-ft @ 3800 rpm
Max horsepower gain: 16.0 @ 6700 rpm
Max torque gain: 12.5 lb-ft @ 6700 rpm
3000-8400 rpm accel.: 8.52 sec.
Temperature: 79 F
Humidity: 10%

Parts: K&N drop-in filter
Installation time: 0.5 hours
MSRP: $69


  • Great bang for the buck
  • Epcp_1104_05_o+audi_RS4_gruppem_intake_vs_k_and_n_drop_in+audi_RS4_badge Photo 6/13   |   Audi RS4 GruppeM Intake VS. K&N Drop-In - Proven


  • Considering the inexpensive price, none
  • Test Notes
    In Part 1 (Feb. ’10) we tested this K&N filter, only with the stock exhaust system and the Revo Stage 1 software. It netted a peak gain of 10.2 hp and 7.0 lb-ft of torque at 7500 rpm. This time, with the current exhaust mods and Stage 2 software, the filter was good for a little more power.

    GruppeM Ram Air Intake

    Epcp_1104_06_o+audi_RS4_gruppem_intake_vs_k_and_n_drop_in+gruppem_ram_air_intake.jpgepcp_1104_06_o+audi_RS4_gruppem_intake_vs_k_and_n_drop_in+gruppem_ram_air_intake.jpg Photo 7/13   |   Audi RS4 GruppeM Intake VS. K&N Drop-In - Proven

    Test 2

    Peak power: 361.1 hp @ 7500 rpm
    Peak torque: 306.2 lb-ft @ 3700 rpm
    Max horsepower gain: 12.1 @ 8300 rpm
    Max torque gain: 7.6 lb-ft @ 8300 rpm
    3000-8400 rpm accel.: 8.44 sec.
    Temperature: 82 F
    Humidity: 10%

    Parts: Carbon-fiber airbox, conical filter, filter adaptor, machined MAF housing, stainless Allen bolt clamps, breather kit, mounting hardware
    Installation time: 1.5 hours
    MSRP: $1,695


  • Top-notch quality
  • A larger airbox with fewer restrictions to the air inlet
  • Nice installation hardware
  • Lots of attention to detail
  • Dresses up the engine
  • Big underhood roar
  • Cons

  • Not cheap!
  • Test Notes
    These gains show the improvement over the K&N drop-in filter. Compared to stock, the peak gains were 21.5 hp at 8300 rpm and 15.1 lb-ft of torque at 6700 rpm.

    Epcp_1104_07_o+audi_RS4_gruppem_intake_vs_k_and_n_drop_in+air_intake_system Photo 8/13   |   Audi RS4 GruppeM Intake VS. K&N Drop-In - Proven

    As with the baseline and K&N runs, we had to give the car several runs to adapt to its new upgrade. Also, by now the ambient temperature had risen 6 degrees but the car still showed power gains.

    After a few more pulls we actually saw a bit more power, but the data was discarded because it was while the car was being brought up to temp again, and the coolant and oil temperatures were still 10 degrees lower.

    The icing on the cake is a new, unmistakable roar coming from new intake at all rpms.


    Audi RS4s are very finicky on the dyno and must be run repeatedly before seeing usable numbers. Until then, power fluctuates, sometimes showing a loss.

    At last, the K&N proved to be a great bang for the buck. But as it is with most cars, each additional horsepower gets more expensive. At least in the case of the GruppeM Ram Air intake, the average horsepower gain was double that of the drop-in filter, and nearly equaled all the previous exhaust and software mods combined in the top end.

    To test the validity of the Ram Air designation, we also tested the car on the road, with the exact same starting point, ambient temperature and fluid and air temps. Sixty-120 mph runs with only a Third to Fourth gear shift was used for ease of repeatability. If the GruppeM was going to improve the ram-air effect, this test would show it.

    Epcp_1104_08_o+audi_RS4_gruppem_intake_vs_k_and_n_drop_in+air_intake_system Photo 9/13   |   Audi RS4 GruppeM Intake VS. K&N Drop-In - Proven

    With an average baseline of 10.92 seconds with the stock filter, the K&N drop-in improved this average to 10.85 seconds. The GruppeM averaged 10.64 seconds, nearly quadrupling the gain the K&N drop-in had over the stock setup.

    For those unwilling to spend the GruppeM price, a K&N drop-in should surely find its way into every other RS4. But the GruppeM provides more power, more underhood bling, and an improved intake roar. Is it worth it? This owner sure thought so, and for the same reason he ponied up the extra $20K over the regular S4.

    60-120 mph road test

    (3rd-4th gear, two-run average)
    Temperature: 64 F
    Baseline: 10.92 sec.
    K&N drop-in: 10.85 sec.
    GruppeM Ram Air: 10.64 sec.

    Epcp_1104_09_o+audi_RS4_gruppem_intake_vs_k_and_n_drop_in+revo_technik_SPS Photo 10/13   |   Audi RS4 GruppeM Intake VS. K&N Drop-In - Proven

    Revo Technik SPS
    Revo Technik’s Stage 1 91-octane software took this car from a stock 321whp to 328 whp, with a peak gain of 13.5 hp and 13.0 lb-ft of torque at 6100 rpm and 5200 rpm, respectively.

    Epcp_1104_10_o+audi_RS4_gruppem_intake_vs_k_and_n_drop_in+magnaflow_exhaust Photo 11/13   |   Audi RS4 GruppeM Intake VS. K&N Drop-In - Proven

    MagnaFlow exhaust
    The all-stainless MagnaFlow exhaust shaved 20 lb off the rear of the car and saw a good low-end gain, which peaked 8.6 hp and 12.5 lb-ft of torque at 3600 rpm. While peak power didn’t improve, the peak torque went up by 10 lb-ftfrom 276 to 286 lb-ft. The sound improved to a throaty V8 snarl as well.

    Epcp_1104_11_o+audi_RS4_gruppem_intake_vs_k_and_n_drop_in+statmosphere_milltek_downpipes Photo 12/13   |   Audi RS4 GruppeM Intake VS. K&N Drop-In - Proven

    Statmosphere’s Milltek downpipes with high-flow cats was good for an additional 10 lb-ft of torque, taking it to a peak 296 and the horsepower up a few more ponies, to 338. Peak gains were 9.4 hp and 10.7 lb-ft at 4000 rpm, and they shaved an additional 12 pounds of weight. By now the low- and mid-range gains were obvious during cruising, and the V8 roar had grown even deeper.

    Epcp_1104_12_o+audi_RS4_gruppem_intake_vs_k_and_n_drop_in+revo_stage_2_software Photo 13/13   |   Audi RS4 GruppeM Intake VS. K&N Drop-In - Proven

    With Milltek downpipes and MagnaFlow exhaust in place, Revo’s George Osmun loaded up a new file, taking the car from 338 to 342 whp with Revo’s Stage 2 software. Peak gains were 7.7 hp and 4.9 lb-ft of torque at 8200 rpm.


    Rancho Santa Margarita, CA 92688
    Victor, NY 14564
    Clawson, MI 48017
    Revo Technik USA
    Buford, GA 30518
    Modified By KC
    Merriam , KS 66203
    Cleveland, OH 44135
    GruppeM USA
    Skokie, IL 60076
    By Pablo Mazlumian
    81 Articles



    For years Honda/Acura owners have been using chassis codes to refer to their cars, but because chassis codes can vary based on a number of factors, there's a good chance that they've been using the wrong labels
    Aaron BonkJul 27, 2020
    Eventuri has been a favorite among the most elite and highest-performing European sports cars out there. We see if the hype behind them is real using Sam's Supra.
    Sam DuJul 23, 2020
    A blowoff valve is designed to protect the turbo against damage. They just happen to make a loud sound while doing it! But the noise they make shouldn't be what you're most concerned about
    Evan GriffeyJul 16, 2020
    Tires are the most important investment you can make when it comes to your safety and car's performance. There's a lot of factors that go into choosing the right tire, some of which may matter to you more than others
    Sam DuJul 13, 2020
    At its most basic level, porting the intake and exhaust ports on a rotary engine is the same as porting the cylinder head(s) on a piston engine, in that the objective is to improve airflow in and out of the combustion chambers.
    David PratteJul 9, 2020
    Sponsored Links


    TO TOP