This discussion goes back a few years.
For some of you who are new to this forum most people did not go to stage 1 because of increased horsepower/torque performance expectations but to make the engine run better. With my original stock exhausts they were so restrictive the header pipes would glow red after driving for awhile and the engine would run rougher with more vibrations created throughout the vehicle. This was substantially improved going to stage 1. And yes there is a modest horsepower/torque enhancement.
I went for MMC Stage 1 for the same reason. In 7,000 miles on the standard exhaust I doubt I hit the rev limiter more than a handful of times as it was so strangled at the top end. Fitting the air filter alone made no discernible difference.
On my first drive after fitting the Stage 1 exhausts I inadvertently hit the limiter about 20-30 times as it just revved so freely and was so much smother. I think opening up the standard exhaust or going for any of the stage 1 exhausts is the best single modification for the M3W bar none.
