I recently fitted a Japspeed and hate it! Way too loud imo, it's the deepness that I think is the problem make my whole car vibrate! It's better with the bung in but not great! Glad I paid very little for it, I was thinking getting a smaller back box made up at a custom place as the rest of the system is spot on, I think it's just the back box. Also had a hks and 5zigen systems in the past and they were both much better very subtle wish I had never sold them!