Das ist nicht die neuner Box, das dürfte ne Racebox sein.
Hi Flemming! First: Sry for my bad english, but i will try
If i am right this is a "selfmade" raceairbox, which uses the gastank as cover. For this the gastank have to be modified (open from the ground and welded new).
If you are able to do this, it will benefit the performence, espacielly the response.