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resurrecting to say thanks :)
only resonated exhausts are legal here, if stock was already 3" I would not have bothered but +0.25" is worth having for a future tune
 

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resurrecting to say thanks :)
only resonated exhausts are legal here, if stock was already 3" I would not have bothered but +0.25" is worth having for a future tune
The general consensus is that the stock flows great and aftermarket will only get you noise. Unless, you're going for big power of course.

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Blog : Focus RS Turboback Exhaust Results : Stratified Automotive Controls

This is the write up that up that you want, explains everything you'd want to know about if you should or shouldn't upgrade the exhaust . Best of luck!
I trust the folks at Stratified but I am having a hard time believing the claimed performance gains, based upon what I have seen from other catbacks that don't claim any hp increases. We are to believe that the CP-E system nets 21whp? CP-E makes very nice parts (I had their Intercooler on my FiST) but I don't see how they magically make 21whp when other vendors are netting any gains. Forgive me if this is covered in another thread, but has anyone else tested this system for gains?
 

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I trust the folks at Stratified but I am having a hard time believing the claimed performance gains, based upon what I have seen from other catbacks that don't claim any hp increases. We are to believe that the CP-E system nets 21whp? CP-E makes very nice parts (I had their Intercooler on my FiST) but I don't see how they magically make 21whp when other vendors are netting any gains. Forgive me if this is covered in another thread, but has anyone else tested this system for gains?
The torque targets, timing, charge air temperatures, and fueling were the same between these runs. However fuel trims tell us a little bit more about what is going on. They indicated that the ECU had to add 1-2% more fuel to achieve the same air fuel ratios with the catback versus the bone stock car. This means the catback actually improved the volumetric efficiency of the engine. This means more air was entering the cylinders and producing more power. This, along with a drop in pumping losses accounts for the performance gains.
From the article/blog, I think it has to do with the fact stratified is comparing tune to tune, ie. not the off the factory tune. By having torque targets be more aggressive in the stratified tune, the car adds fuel which nets you the extra horsepower. Most manufacturers quote gains on the stock tune so it's apples to apples. the stratified blog post is specific to understanding the bottlenecks within the car when building for power. Edit: Want to be clear, stratified used the same tune for both runs, but it was their tune, not the factory...a 3" exhaust simply helps lessen the pumping loss of the engine, freeing up the horsepower. I'm sure any 3 inch exhaust with any bit of good design would net a similar increase under any tuner.

Cheers,
Chris
 
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