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Currently on my ST I’m running an injen CAI, AWE track edition catback exhaust, and the turbo smart BOV. I’m wondering if I get a catless downpipe will I need a tune? Bc I’m running stock tune right now and want to keep it that way.
 

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Currently on my ST I’m running an injen CAI, AWE track edition catback exhaust, and the turbo smart BOV. I’m wondering if I get a catless downpipe will I need a tune? Bc I’m running stock tune right now and want to keep it that way.
You don't need a tune, but you are not getting any benefit from those modifications without one. The factory map is torque targeting and once it sees the maximum allowed torque it dials back the timing/fueling/boost.
 
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Discussion Starter · #3 ·
You don't need a tune, but you are not getting any benefit from those modifications without one. The factory map is torque targeting and once it sees the maximum allowed torque it dials back the timing/fueling/boost.
So if I do it it won’t do any harm to the engine
 

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So if I do it it won’t do any harm to the engine
Correct. You'll not harm anything with just running the parts without the tune. I was basically fbo (less catback) without a tune for a while and all I noticed was my max boost pressure kept going down as I added more mods thanks to torque targets. Had great mileage, but just no more power.

The JST tune really woke it up, though. 😁
 
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Technically you don't need a tune for any of those mods and really there's no performance gain from them. However normally you would tune for a catless dp but you don't have to. It will run a little bit rich. And you'll also throw a code for oxygen sensor inefficiency which if you have annual emissions testings as part of an inspection you'll fail. You do have the testing and you want to run the downpipe without a tune you can install a defouler . I recommend the vibrant j-style defiler. That'll make the computer think that you still have a catalytic converter and keep it from throwing the code. I believe I'm running the medium size insert. I had the tuner leave my rear o3 sensor on so I can pass emissions with a stage 3 tune installed.
 
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