I weighed similar options, and I started with used corsa mufflers. They have a more exotic tone that I like. Then I added a bimmerworld x pipe tuned with Epic, which gave a great bump in power+torque and a great tone(not stupid loud). I can still hear induction noise so I’m very happy with it. (Sound clip attached)
I contemplated various plenum+intake options, but the most performance is in exhaust work for this platform. I did swap in a BMC filter, and added $20 cowl filters that added a bit more induction noise.
I’ll eventually get a Haimus or carboproject plenum, but I’m very happy with how it sits!
I spent just about 3k for the full exhaust+tune.
Corsa +bimmerworld exhaust