i just recently sold my eisenmann race for an akra and to tell you the truth, i love both!
the eisenmann race was a deep deep note, and around 3000 rpm it would drone slightly. i didn't mind the loud exhaust note because i used to have a NSX with a loud (but amazing sound). the akra is mild to me if anything...the only time it's loud is the start up/warm up of the car, it sets off alarms lol.
anyways overall the sound from both, i just like the weight savings and look of the akra, which is why i sold my eisenmann.
happy motoring with either one you choose!