hi all I'm new here.
Just brought a 09 s3 it has some mods done already.
Miltek cat back. Forge twinintake. Forge dv.revo stage 2.
My quistion is. It has milltek cat back with stage 2 map on it .
If I put a miltek down pipe with high flow cat do it need to retune map to suit???
Or the stage 2 is already cover/map on high flow down pipe and
it just make it breath better and no need to retune map??
Will it trigger the CEL with high flow DP?!!
Many thanks for help