Changing the ECU is a similar process to retunng the factory ECU... They both allow for tuning for the most performance out of the mods

Retuning (reflashing) is the way to go if you dont want to go too far with mods and even if you do

A new (aftermarket) ECU is more for the serious applications yet many have run some serious setups on reflashed ECU's

Reflashing is also quite a bit cheaper...

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The performance will still be there but the ECU will shut it down because its outside of the factory peramiters.
You have to have a reflash.
You will need a retune with all (if you want to be safe) breathing mods.

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