Golf mk4 1.8T ARZ

[spidermen]

Hello

when I replace the flow meter with a larger 3.5 inch, do I have to make any changes to the ecu in the engine control unit?

my car golf mk4 2000 1.8t ARZ

[Lambda1]

Sure you need to do.
Enough informations about in web.

[tepSIJA]

You must make changes to map, otherwise ecu will be confused. Talk with tuner about changes he will know what to do, otherwise ecu will se "less" air ..