These are impressive gains from some rather simple mods. Though I’d guess most of us aren’t going to want to run stacks. Nonetheless, you can see how hamstrung the bike is from the factory.
I’ve done the DNA airbox mod and Brentune to positive seat-of-the-pants results. I’d be super curious to see someone Dyno across the few different off-the-shelf exhausts (Vance, Jekill, couple others) to see where the bang for the buck lies. If those Vance pipes can be had at 25% off (or better, depending on what deals bmw runs throughout the year) and can pop a few ponies in, that’s a winner for sure. Trouble right now is there doesn’t seem to be anyone who has swapped pipes who can speak much more about them than the sound benefits.