Stage 1:
- Power: gets the power back to the level before fitting urban cooling kit, or slightly higher
-
I'm not aware that the Urban Cooling kit reduced power.
MMC S1 frees the engine up and probably gives a similar increase in power to the G56.
Subjectively, at idle and low revs, MMC and G56 are similar volumes, just slightly different sounds.
In terms of long distances - I've been from the UK to Switzerland and back (around 2,000 miles) once with stock exhausts and again with MMCS1 and didn't notice any difference in noise comfort. As you say at motorway speeds it's all pretty much road and wind noise.
The lowest cost alternative is drilling out a baffle (or 2) which improves the engine but is noisier than MMCS1 or G56
Finally MMC S1, G56 and drilled baffle all run OK with the standard ECU.
