I realize this is an old thread. But I'm curious if removal of the cats and baffles plus the addition of a less restrictive intake, a) essentially results in a 'MMC Stage 1' upgrade, b) if it requires an ECU tune or does the (US-spec) ECU have enough bandwidth to adapt, and c) if a G56 Stage 2 upgrade that includes an ECU tune would be happy layering on top of the 'homemade' Stage 1.

Asked another way, would this mod save the cost of a Stage 1, particularly if the goal is Stage 2 anyway?

'17 M3W:
'08 Ural Gear-Up