[Frozen Fractals]

Trying to decide on a tune and exhaust for my (new to me) 2018 540i xDrive.

For the tune, I've been doing some reading and it seems like there's two kind of tunes out there: piggyback and flash tune. The most popular piggyback seems to be the JB4 and I've seen bootmod3, RK, Dinan and of course MPPSK as popular flash tunes. The JB4 seems the most primitive, but also cheapest and easiest to remove if I need the car serviced (it is CPO). However, I've read that it might not be as "smooth" as a flash tune. MPPSK would keep my warranty intact, but I am not sure about replacing the torque converter or the M Performance Exhaust (more on that later). I've read a lot of good things about bootmod3 and would most likely go that route if going with flash tune. I am not looking to max out the power/torque and would be happy with around 400HP. Not sure if I want to do any bolt-on mods (downpipe with high flow cat, intake, etc.) either due to warranty situation. I also live in CA, so I will be using 91 Octane fuel. Thus, I'm leaning towards either JB4 or bootmod3. Any suggestions?

For the exhaust, I have looked at MPPSK (MPE), ACS, Remus and Armytrix. I've read that the MPE is kind of a let down for the money and drones at highway speeds (something I'm trying to avoid) due to lack of valves. I like the sound of Remus and leaning towards it, but I wished they offered black exhaust tips that aren't insanely expensive (the titanium one). Still unsure about the exhaust, tbh.