GrimmSpeed Cold Air Intakes - Legacy GT 2005-2009

For years you've been asking us for intakes, and for years we've silently worked to create a solution that sets itself apart from the rest. We examined and tested current offerings, and identified their shortcomings. We formed theories, and over months of testing designs we proved them. Combined with our advanced research and development program, we fully utilized our engineering resources to design and manufacture what we believe is the most comprehensive intake solution available for the 2005-2009 Subaru Legacy GT.

Quick Specs

• Hybrid Cold Air/Short Ram Design - Combining the advantages and eliminating the negatives of both traditional intake designs
• Air straightener - Dimensionally mimics the factory configuration for accurate MAF sensor readings
• MAF sensor location - Inside heat shield, isolated from engine bay heat
• Custom reusable high flow air filter - Integrated velocity stack entrance smooths incoming air
• Made in the USA - Right here in Minnesota, in fact
• 30min Installation - Extremely simple with our written and video guides

Design

Based on our testing and research, design requirements for this intake became simple. The MAF sensor must be protected from the heat of the engine bay for more accurate readings. The filter must not be close enough to the ground such that water/hydrolocking are a concern. The MAF sensor must be placed relative to the filter and air straightener, similar to the OEM airbox, so that airflow readings are consistent and reliable. The intake tube must be no longer than necessary with minimum bend angle, to reduce restriction. The heatshield must provide sealing between the induction area and the hot engine bay to keep air intake temperatures low. The GrimmSpeed intake shown here achieves each of these requirements and more. What is accomplished is a true hybrid of traditional Cold Air Intakes and Short Ram Intakes, with all the advantages and none of the compromises.

The two engineering studies above illustrate the importance of understanding how air moves within the entire intake system. The figure on the left shows how the GrimmSpeed intake design compares to other intake designs with respect to MAF placement and how that affects airflow readings. Since the MAF sensor samples the velocity of incoming air to measure flow in the center of the tube, having an accurate velocity profile at the sensor is the only way to accurately measure airflow. The figure on the right shows the importance of considering how air moves within the heat shield or box, prior to entering the filter. The GrimmSpeed heat shield geometry keeps air from collecting in sharp corners and 'feeds' the air filter uniformly. This uniform air distribution contributes to more accurate MAF readings, but also reduces filter restriction and increases time between filter cleanings due to even "filter loading." And while the airbox is doing it's job of increasing performance, it's also cleaning up the engine bay and looking good.

Materials

In true GrimmSpeed fashion, no corners were cut in the fabrication of each and every one of these intakes. The aluminum heat shield is laser cut, CNC bent and riveted together before receiving a heavy duty black texture powdercoat. MAF flanges are CNC machined from 6061 aluminum and the intake tube is fabricated from custom bent tubing, made specifically for our application, to provide the perfect MAF diameter. The air straightener is laser cut from the same 6061 material and tumbled before the entire assembly is TIG welded by our expert welders. After welding, each tube receives the same heavy duty powdercoat and is inspected and cleaned to ensure maximum performance and reliability.

Performance and Tuning

This intake was designed with tuners in mind! The consistency of the airflow through the MAF sensor makes this intake very predictable and is as easy to tune as the stock airbox. Intial dyno testing and design theory validation was completed on our 2012 WRX, equipped with a GrimmSpeed 3-Port EBCS, Catted Downpipe, Catless Uppipe and TMIC. We then worked with a local product tester and his 2005 Legacy GT wagon to verify performance on the intended model.

The chart on the left shows a comparison of the same car with a stock intake and stock tune, followed by the stock intake with the applicable COBB Stg2 OTS Map. Then, the GrimmSpeed intake was installed and the MAF scaled properly for use with the same map. Lastly, wastegate duty cycle was also scaled to increase boost pressure from 15.5psi to 18psi.

The chart in the middle shows the GrimmSpeed Intake vs. Another Popular Intake running on the same recommended COBB OTS Stg2 93OCT +SF Map. Using this tune, the GrimmSpeed intake provides an additional 21whp at the peak and up to 30whp earlier in the powerband. It should be noted that both of these runs were very rich and left quite a bit of power on the table. This is the reason that we recommend a professional tune.

Finally, the chart on the right is similar to the chart above, but the GrimmSpeed intake has been custom dyno tuned by DB Performance in Rogers, MN. The additional 5lbs of boost safely nets 40whp and nearly 50ftlb of torque. This image has been resized. Click this bar to view the full image.

For the most complete summary of the 2005 Legacy GT verification dyno results, follow this link.

Includes everything

• 1x Intake Tube
• 1x High-flow Oiled Filter
• 1x Hump Hose Connector
• 1x Heat Shield Assembly
• 3x Hose Clamps
• 2x MAF Flange Screws
• 3x Precut Rubber Sealing Strip
• 1x MAF Wire Grommet

Fitment

• 2005-2009 Subaru Legacy GT