2008 Mitsubishi Evolution X - Uncorking More Power

With An AMS Intercooler And A Cobb Tuning Turbo-Back Exhaust, The Evo X Is Finally Able To Unleash Its Real Horsepower Potential.

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Project Evolution Last month, with just an intake and a Road Race Engineering tune by Mike Welch, the EVO X picked up a solid 51 whp and 35 ft-lbs of torque over stock. The final peak numbers came in at 312 whp and 318 ft-lbs, but Mike said there's more horsepower to be made by freeing up the exhaust flow and providing adequate and consistent cooling with a better front-mount intercooler. I had my homework assignment and got right down to it.

After doing some research and comparing brands, my intercooler of choice was the AMS unit because of its cast end tank design, excellent fitment and 80 percent increase in flow area over the stock intercooler. The bar and plate core measures 12.4x20 inches wide and is 3.5 inches thick while flowing 1,250 cfm. Plus, it's the same intercooler AMS runs on its 750-whp time attack EVO X - meaning you'll never have to upgrade it again.

To go along with the FMIC, I also picked up the AMS upper and lower hard piping kit. The factory piping consists of many rubber pieces that tend to expand under high boost pressures and can become prone to popping off as the rubber deteriorates over time. The AMS four-ply couplers can handle 50+ psi of boost with ease and the lightweight aluminum hard pipes all have bead-rolled ends to ensure they don't blow off under high load. If you've ever had an intercooler pipe pop off during driving, it's not a fun experience (especially when you don't have any tools with you). I went with the AMS wrinkle black powdercoated piping for a stealth look in the engine bay, but if chrome is what you fancy, AMS offers that option as well.

I tackled the installation myself with some simple handtools and no hoist. It took a little over two hours, and because the AMS pieces fit like stock I didn't have to fight to make anything work. The AMS intercooler, despite being much larger and thicker than the stocker, doesn't require trimming or removal of the factory brake ducts located on the main inlet of the front bumper - unlike some of the other intercoolers on the market, which may require modifications to fit.

Upgrading the exhaust was next on the list and it's arguably the single most relevant modification anyone does to their car. While we all want to convince ourselves that it's the performance aspect that's the driving force behind the decision, we all know the look and sound of the system are equally (if not more) important. These days, most aftermarket exhaust systems flow exceptionally well - one 3-inch system isn't going to provide huge horsepower gains over another 3-inch exhaust. So the decision of which system to go with starts coming down to personal preference more than horsepower gains.

That being said, there will always be exhaust systems that fit better than others, so be wary of buying cheap units because they'll give you plenty of headaches down the road. Remember that the EVO X has a large plastic diffuser that almost wraps around the exhaust. If the fitment is off, you can expect some nice burn marks to develop quite quickly. Avoid all that by going with a reputable and trusted brand like I did.

Cobb Tuning's 3-inch SS after-cat exhaust has very few bends in the piping and with a high-flow, straight-through muffler design, it not only meets the strict 95dB sound requirement of most states but it flows well enough to make plenty of power. Furthermore, it tucks up against the chassis for maximum ground clearance, so if you want to go low, this exhaust won't hold you up. My main reason for choosing the Cobb system was its stock-like appearance. You won't know that my exhaust is modified until you get up close to it. The etched tips with the Cobb logo mimic the factory pieces exactly. The tone was also a huge selling point; it's got a nice low rumble to it at cruising and idle. Mash on the throttle and the note picks up considerably, but not to the point of being obnoxious. I can try to describe it all day long, but if you go to youtube.com/modifiedmag you can listen to a sound clip and really understand what I'm talking about. Cobb isn't making many of these systems, either, so you better grab one before they become a heavily sought-after unit.

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