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okay so i have a 2017 wrx and im just wondering why i need a tune for a turbo back exhaust. if i was to purchase one id get one with a high flow cat. suggestions and explanations are welcomed.
 

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Backpressure and flow changes
 

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There will be less back pressure on the turbine, which will in turn make the turbo work more efficiently. I haven't really looked into exactly how the new ECUs are set up, but the biggest issue with previous years was that the increased efficiency would allow the engine to hit load levels that simply were not tuned in the stock map. Basically, once the car got up and going it would hit a point where the computer didn't know what to tell the engine to do anymore.. bad things would happen as a result.

Not to mention that even if you didn't need tuning to prevent engine damage, you wouldn't get much power increase from the new exhaust anyways. The modification allows for more aggressive tuning, which is where you get the performance increase.
 

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There will be less back pressure on the turbine, which will in turn make the turbo work more efficiently. I haven't really looked into exactly how the new ECUs are set up, but the biggest issue with previous years was that the increased efficiency would allow the engine to hit load levels that simply were not tuned in the stock map. Basically, once the car got up and going it would hit a point where the computer didn't know what to tell the engine to do anymore.. bad things would happen as a result.

Not to mention that even if you didn't need tuning to prevent engine damage, you wouldn't get much power increase from the new exhaust anyways. The modification allows for more aggressive tuning, which is where you get the performance increase.
And don’t forget to replace intercooler hose that usually blows out stage 2 or is that different with 2.0’s??


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By altering the flow with an aftermarket turboback exhaust, you're throwing off the boost / ignition / fueling / AVCS (cam timing) tables that are programmed into the ECU, enough that engine failure no longer becomes a matter of "if", but "when".

You have a $30K vehicle. You're spending $1000+ on a turboback exhaust. Are you really arguing over $650 (less, if used) purchase of a Cobb AP? An engine replacement (due to failure to properly calibrate) is a LOT more than $650. That shiny turboback exhaust you installed means that you'll be paying for the repair out of pocket.
 
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