Find the most expensive exhaust you can find. That's the best one.
Everything else is just noise??
I think Akra's sound tinny and pingy due to their construction. Well engineered, well manufacturer, exceptional quality... For sure, but there are tons of exhausts that can provide modest hp increase while producing a fantastic exhaust note.
I have a Dinan and turner mids. I love the way it sounds, not loud, no drone, and good hp increase.
There's plenty of exhaust setups that will provide some power and sound while not being obnoxious.
IMHO spending 5-6k on an exhaust is silly when you consider you can buy a SC for that much.. Instead your getting maybe 20hp and some titanium.