after searching and reading i still didnt really get what ecu to use on the a6. when changing from an f22a4 to an f22a6 could i keep the a4 ecu?

 

why are you going from an a4 to an a6? its only 10hp, not worth it in my opinion. hope you didn't do an engine swap, and you just changed the header, cuz thats all the difference is. at least i think tahts all the difference is

 

oh i did the swap already... i did it because my a4 was all f'd up, i just wanna know if i should be using the a6's ecu

 

your old A4 ECU is fine.