K&N Performance High Flow Filter
Pros
When it comes to the hundreds of various cold-air and short ram intakes on the market today, none work as well for the EVO as a stock replacement filter when knowlegable tuning isn't involved. K&N replacement air filters are designed to fit right into the standard OEM Mitsubishi Evolution air box. With no necessary modifications required by the owner, the replacement filter is installed by simply removing the four factory clips and popping the unit in place. Using a urethane rubber construction to improve the air box seal over the factory element, the K&N filter's construction consists of four to six sheets of cotton gauze layered between two sheets of aluminum wire mesh.
Cons
We were reluctant to see any gains using a replacement filter on the EVO as most of our previous tests on other EVOs had been performed using a cold-air intake system. Luckily for the EVO community, we were well aware of the many problems that the cold air intakes had caused on EVO's sporting a stage 1 or stage 2 setup with basic bolt-ons. The more common problems we found among EVOs using an aftermarket filter was associated with the "finicky" factory ECU that nets either a serious loss or minimal gain in horsepower without addressing proper tuning. The drop-in element filter was used to showcase a gain in horsepower throughout the entire powerband without any necessary tuning, while eliminating the loss in bottom end and midrange power which was a common occurrence with aftermarket intakes.
Parts
Performance high-flow air filter
Tools
None
Installation Time
80 seconds
Notes
A series of dyno runs were performed using the K&N replacement filter to ensure the power gains we had obtained were indeed not a fluke. Being pessimists when it comes to producing true power, we ran the filter- equipped EVO numerous times on the dyno to make sure the ECU did not compensate for the filter causing an unwanted drop in horsepower or even worse, a loss over stock. To our delightment, the filter performed exceptionally well as dyno charts show as a smoother graph throughout the powerband until 7400rpm, where it was obvious that tuning would obviously help to quell this boost-dependant vehicle. We found a gain of 12hp and 13 lb-ft of torque improvement over our baseline run while peak horsepower improvements netted 4.3hp and 3.1 lb-ft of torque.
Dyno 2:
K&N Performance High Flow Filter
PEAKHP 262.0 / PEAKTQ 255.4
Horsepower Gain
1500 to 3500 HP range: 0 to 1
3500 to 5500 HP range: 0 to 7
5500 to redline HP range: 3 to 12
Torque Gain
1500 to 3500 TQ range: 2 to 3
3500 to 5500 TQ range: 10 to 5
5500 to redline TQ range: 13 to -2