[BadakVT]

I have the full turbo-back Akrapovic kit and it's too loud for me with the valve open. Drones as well with the decat DP and fully open valve. Too bad the valve is only open/closed and unlike Remus valve with 4 different opening settings.

I have also been having problems with the valve kit (mine is quite old), so recently I have taken off the valve and replaced it with the connecting pipe. But with the closed connecting pipe, it became too quiet. Finally I cut about 1/4 of the connecting pipe's blocking plate and now it sounds perfect.

As for the loud start up, definitely get MHD and use it to disable cold-start (catalytic warming).

In short, if not planning to get downpipes, just get the slip-on without the valve kit and completely take off the blocking plate on the connecting pipe.
If planning to get downpipes, either get the valve kit or just play around with opening the blocking plate until you get your preferred noise level.