{"product_id":"process-west-top-mount-intercooler-subaru-wrx-sti-gd-2003-2005","title":"Process West Top Mount Intercooler - Subaru WRX STI GD 2003-2005","description":"\u003ch2\u003eProcess West Top Mount Intercooler - Subaru WRX STI GD 2003-2005\u003c\/h2\u003e\n\n\u003cp\u003e\u003cstrong\u003eApplication:\u003c\/strong\u003e Subaru WRX STI GD 2003-2005\u003cbr\u003e\n\u003cstrong\u003ePart Type:\u003c\/strong\u003e Intercooler Kits\u003c\/p\u003e\n\n\u003chr style=\"margin: 20px 0; border: 0; border-top: 1px solid #000;\"\u003e\n\n\u003cp\u003eThe Process West Top Mount Intercooler was developed with a single goal — to be the very best aftermarket top mount intercooler for the WRX and STI, without compromise.\u003c\/p\u003e\n\u003cp\u003eEvery competitor product was studied. Every common mistake was addressed.\u003c\/p\u003e\n\u003cp\u003eThe most common error in aftermarket top mount intercooler design is supplying a larger core without properly sized ducting to match. Fitting a larger intercooler and leaving the factory bonnet splitter in place means up to 50% of the new core receives no ambient airflow. A waste of the upgrade.\u003c\/p\u003e\n\u003cp\u003eThe images below demonstrate this using the Process West intercooler installed in a 2006 Forester XT, with the factory splitter placed over the core as if the bonnet were shut. The result is evident.\u003c\/p\u003e\n\u003cp\u003e\u003cimg style=\"font-family: -apple-system, BlinkMacSystemFont, 'San Francisco', 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif; font-size: 0.875rem;\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/products-18-4.jpg?v=1772691181\" alt=\"\" width=\"452\" height=\"340\"\u003e\u003c\/p\u003e\n\u003cp\u003eThe solution is clear: a splitter sized specifically for the upgraded core, ensuring 100% of the core receives full ambient airflow.\u003c\/p\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/products-18-5.jpg?v=1772691245\" alt=\"\" width=\"454\" height=\"340\"\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cem\u003eProcess West intercooler and splitter\/combination showing 100% of the new larger intercooler with full ambient airflow over the entire core.\u003c\/em\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/products-18-6.jpg?v=1772691290\" alt=\"\" width=\"454\" height=\"340\"\u003e\u003c\/p\u003e\n\u003cp\u003eThe image above shows a 2005 WRX with the bonnet scoop removed and the factory splitter still in place. The white line marks the actual footprint of the upgraded intercooler beneath it. The mismatch is obvious. Upgrading the intercooler without upgrading the ducting achieves very little.\u003c\/p\u003e\n\u003chr style=\"margin: 20px 0; border: 0; border-top: 1px solid #000;\"\u003e\n\u003ch3\u003eCore thickness matters\u003c\/h3\u003e\n\u003cp\u003eThe second mistake we commonly see is \u003cem\u003ebuilding an intercooler that's too thick\u003c\/em\u003e. Bigger core dimensions make for compelling marketing, but physics tells a different story.\u003c\/p\u003e\n\u003cp\u003eA top mount intercooler sits at 90 degrees to ambient airflow. On a boxer engine, that air has already made a 90-degree turn through the bonnet scoop before it reaches the core. Asking it to then push through 114mm of intercooler core is too much to ask. The result is restricted airflow, poor heat exchange, and high intake temperatures.\u003c\/p\u003e\n\u003cp\u003eThe Process West core is 90mm thick. That is the optimum balance between cooling surface area and airflow resistance, and it shows in the outlet temperatures and power figures.\u003c\/p\u003e\n\u003chr style=\"margin: 20px 0; border: 0; border-top: 1px solid #000;\"\u003e\n\u003ch3\u003eY-pipe distribution\u003c\/h3\u003e\n\u003cp\u003eMost aftermarket Y-pipes distribute charge air unevenly, with one well-flowing duct and a poorly considered second outlet. The Process West Y-pipe is engineered for even charge air distribution across the full width of the intercooler core.\u003c\/p\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/products-18-2.jpg?v=1772691350\" alt=\"\" width=\"475\" height=\"356\"\u003e\u003c\/p\u003e\n\u003cp\u003eTogether, the correctly sized core, splitter, and Y-pipe form a complete top mount intercooler system for the Subaru WRX and STI.\u003c\/p\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/products-18-3.jpg?v=1772691367\" alt=\"\" width=\"479\" height=\"204\"\u003e\u003c\/p\u003e\n\u003cp\u003eThis picture above shows the complete combination of Y-pipe (underneath), intercooler and splitter.\u003c\/p\u003e\n\u003chr style=\"margin: 20px 0; border: 0; border-top: 1px solid #000;\"\u003e\n\u003ch3\u003eDyno testing\u003c\/h3\u003e\n\u003cp\u003eIt's worth noting that dynos and top mount intercoolers are not an ideal combination. Regardless of fan positioning, airflow into the bonnet scoop on a dyno is minimal. With that said, both the factory intercooler and the Process West upgrade were tested under identical conditions, making for a fair and accurate comparison.\u003c\/p\u003e\n\u003cp\u003eThe test vehicle was an otherwise stock 2005 WRX running a BPM GT exhaust. Stock WRXs of this specification consistently produce around 90kW at the wheels on this dyno. Intercooler outlet temperatures were measured via probe placed in the silicone joiner at the throttle body.\u003c\/p\u003e\n\u003cp\u003eRunning the PW intercooler and splitter first, the baseline power result was 115.5kW, with a peak outlet temperature of 51°C. The factory intercooler was then installed and tested under the same conditions. Maximum power dropped to 107.5kW, and the factory unit's thermal performance was far more concerning than the power figure alone suggests.\u003c\/p\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/products-18-7.jpg?v=1772691446\" alt=\"\" width=\"517\" height=\"387\"\u003e\u003c\/p\u003e\n\u003cp\u003eThis graph (above) shows the before and after power. Note the test number. These 2 runs were back-to-back.\u003c\/p\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/products-18-8.jpg?v=1772691469\" alt=\"\" width=\"518\" height=\"388\"\u003e\u003c\/p\u003e\n\u003cp\u003eIntercooler outlet temperature comparison — Process West (dark line) vs. factory unit (light line). Both intercoolers started at 37°C under identical conditions. The Process West unit peaked at 51°C. The factory unit peaked at 66°C. Results shown after a single run.\u003c\/p\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/products-18-9.jpg?v=1772691495\" alt=\"\"\u003e\u003c\/p\u003e\n\u003cp\u003eA final test measured the effect of back-to-back runs on the factory intercooler. After three consecutive runs, outlet temperatures climbed to 84°C and were still rising. The implications for circuit use are significant.\u003c\/p\u003e\n\u003chr style=\"margin: 20px 0; border: 0; border-top: 1px solid #000;\"\u003e\n\u003ch3\u003eStreet testing tells the most honest story\u003c\/h3\u003e\n\u003cp\u003eTesting tells the most honest story. Intercooler outlet temperatures were measured using a Fluke 87 digital multimeter with a K-type thermocouple positioned just before the throttle body, the same location used during dyno testing. Readings from this setup were consistently within one degree of the dyno's AIT probe throughout.\u003c\/p\u003e\n\u003cp\u003eWith the Process West intercooler and splitter fitted, hard driving through the mountains could not push outlet temperatures above 43°C regardless of how hard the car was pushed.\u003c\/p\u003e\n\u003cp\u003eThe factory intercooler and splitter were refitted and the same route driven under identical conditions. Outlet temperatures peaked at 72°C and were still climbing when testing ended. The difference in the car's response was immediate.\u003c\/p\u003e\n\u003cp\u003eThe numbers speak for themselves. The Process West Top Mount Intercooler is the definitive cooling upgrade for the Subaru WRX and STI.\u003c\/p\u003e\n\n\u003chr style=\"margin: 20px 0; border: 0; border-top: 1px solid #000;\"\u003e\n\n\u003ch3\u003eAvailable Options\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eSilver \u003cem\u003e(PWTMIC05)\u003c\/em\u003e\n\u003c\/li\u003e\n\u003cli\u003eBlack \u003cem\u003e(PWTMIC05B)\u003c\/em\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003chr style=\"margin: 20px 0; border: 0; border-top: 1px solid #000;\"\u003e\n\n\u003ch3\u003eVehicle Fitment\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eSubaru WRX STI GD 2003–2005\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cem\u003eNot sure if this suits your vehicle? Email \u003ca href=\"mailto:sales@coore.com.au\"\u003esales@coore.com.au\u003c\/a\u003e\u003c\/em\u003e\u003c\/p\u003e","brand":"Process West","offers":[{"title":"Silver","offer_id":68139463115056,"sku":"PWTMIC05","price":1470.0,"currency_code":"AUD","in_stock":true},{"title":"Black","offer_id":68139463147824,"sku":"PWTMIC05B","price":1470.0,"currency_code":"AUD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0934\/3156\/2544\/files\/PWTMIC05_e807d63f-5f1a-4567-b898-4d5cadd135f4.png?v=1792541661","url":"https:\/\/coore.com.au\/products\/process-west-top-mount-intercooler-subaru-wrx-sti-gd-2003-2005","provider":"Coore | Performance \u0026 Aftermarket","version":"1.0","type":"link"}