{"product_id":"top-mount-intercooler-subaru-03-07-gd-wrx-06-07-sti","title":"Top Mount Intercooler - Subaru 03-07 GD WRX \u0026 06-07 STI","description":"\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\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 class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eEvery competitor product was studied. Every common mistake was addressed.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\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 complete waste of the upgrade.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\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 self-evident.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003e\u003cimg height=\"340\" width=\"452\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/products-18-4.jpg?v=1772691181\" style=\"font-family: -apple-system, BlinkMacSystemFont, 'San Francisco', 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif; font-size: 0.875rem;\"\u003e\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eThe solution is straightforward: a purpose-built splitter sized specifically for the upgraded core, ensuring 100% of the core receives full ambient airflow.\u003c\/p\u003e\n\u003cp\u003e\u003cimg height=\"340\" width=\"454\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/products-18-5.jpg?v=1772691245\"\u003e\u003c\/p\u003e\n\u003cblockquote\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\u003c\/blockquote\u003e\n\u003cp\u003e\u003cimg height=\"340\" width=\"454\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/products-18-6.jpg?v=1772691290\"\u003e\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\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\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003e\u003cstrong\u003eCore thickness matters.\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eThe second mistake we commonly see is \u003cem\u003ebuilding an intercooler that is too thick\u003c\/em\u003e. Bigger core dimensions make for compelling marketing, but physics tells a different story.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\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 class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\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\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003e\u003cstrong\u003eY-pipe charge distribution.\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\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 class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003e\u003cimg height=\"356\" width=\"475\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/products-18-2.jpg?v=1772691350\"\u003e\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eTogether, the correctly sized core, purpose-built splitter, and balanced Y-pipe form a complete, properly engineered top mount intercooler system for the Subaru WRX and STI.\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-family: -apple-system, BlinkMacSystemFont, 'San Francisco', 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif; font-size: 0.875rem;\"\u003e \u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cimg height=\"204\" width=\"479\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/products-18-3.jpg?v=1772691367\"\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cmeta charset=\"utf-8\"\u003eThis picture above shows the complete combination of Y-pipe (underneath), intercooler and splitter.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003e\u003cstrong\u003eDyno testing.\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eIt is worth noting upfront 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 class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\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 class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eRunning the Process West intercooler and splitter first, the baseline power result was 115.5kW, with a peak intercooler 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 height=\"387\" width=\"517\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/products-18-7.jpg?v=1772691446\"\u003e\u003c\/p\u003e\n\u003cblockquote\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\u003c\/blockquote\u003e\n\u003cp\u003e\u003cimg height=\"388\" width=\"518\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/products-18-8.jpg?v=1772691469\"\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.\u003cbr\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cimg alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/products-18-9.jpg?v=1772691495\"\u003e\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\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\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003e\u003cstrong\u003eStreet testing.\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eReal-world testing 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 class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\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 class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eThe factory intercooler and splitter were then refitted and the same route driven under the same conditions. Outlet temperatures peaked at 72°C and were still climbing when testing was concluded. The difference in the car's response was immediate and noticeable.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\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","brand":"Process West","offers":[{"title":"Black","offer_id":51583600689431,"sku":"PWTMIC04B","price":1470.0,"currency_code":"AUD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0962\/0570\/1399\/files\/20.png?v=1770882261","url":"https:\/\/processwest.com.au\/products\/top-mount-intercooler-subaru-03-07-gd-wrx-06-07-sti","provider":"Process West","version":"1.0","type":"link"}