m3 exhaust stuff always diversifies into a million aspects, akra is great sound, performance and quality material. some will vote for other stuff "as they like".
in the end it's all about what YOU like and not us.
with all my good will, all I can suggest to you is to get a loud axle back and nothing else, or get a relatively quiet exhaust with x-pipe.
akra evo drones, tried, tested. performance? did not really feel the advantage of the weight reduction. but that's my opinion anyway.
i think 99% of the complete systems drone. it disturbs me, but you may like it.
imo i like the tone of m perf and akra slip on. i hate drones. imo the other too loud exhausts look like a peugeot 106 gti with really loud exhaust mods....