We borrowed a friend’s completely stock ’11 STI hatchback for a quick dyno test, just to see how the Stage 1 OTS map performs compared to the factory tune. Turns out Subaru played it awfully safe with its tuning, because Cobb’s Stage 1 map picked up huge midrange power and torque gains from 3,000 to 6,000 rpm, as you can see from the results we got on Advance Powerhouse’s in-house Dynapack hub dyno. Peak gains of 33.5 lb-ft and about 7 whp only tell a small part of the story, since the area under the curve gains in the midrange is massive but trails off at higher rpm as the Cobb map begins to trim boost pressure back to the stock level to protect the engine. But prior to that, boost pressure ramps up to maximum boost pressure of 17.8 psi at 3,750 rpm with the Stage 1 tune, versus a max boost reading of 15.5 psi at 3,250 rpm with the stock map.
Although the increased boost pressure is responsible for most of the power gains, it’s clear that Cobb Tuning has also refined fuel and ignition timing, given how both the torque and horsepower curves are smoother than the stock curves. And both the car owner and I agree that the data collected on APH’s dyno plays out quite dramatically in the real world, where this STI feels way stronger, especially in the midrange during typical blasts at full throttle to dispatch slower moving traffic.
As Andy the owner put it, “This off-the-shelf tune goes way beyond just cranking up the boost. It gave me a smoother powerband and more torque in all the right places for a daily driver. Midrange torque is addictive, turbo lag is unnoticeable, and throttle roll-on is linear. When creeping in First gear gridlock, the car has smoother power and is much less jerky under the foot. Also, any STi owner will tell you about an annoying 2,500-rpm ‘bump’ in the powerband, which Cobb has managed to solve.”
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APH/Cobb on Modified Mag
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