Sir: Your answers are below.
1-All XB12 models across-the-board have the same muffler. Said muffler has the "interactive exhaust valve" which is operated by signals sent from the ECM to the actuator assembly which resides atop the large black plastic airbox inner cover.
2-All XB9 models across-the-board have the same muffler. Said muffler does NOT have the "interactive exhaust valve".
3-All XB12 mufflers will directly bolt up to all XB9 models. All XB9 mufflers will directly bolt up to all XB12 models.
4-All XB9 and 12 mufflers use exactly the same mounting hardware-straps-bracketry-cowling fixtures-cowling mount hardware.
5-All XB12 mufflers can be used on all XB9 models but the interactive exhaust valve must be wired open. NOT recommended.
6-All XB model OEM "non-race" mufflers have 1 single outlet tip exiting left side. Said outlet exactly the same except X-XT-XP-Stt...which has a slightly longer and curved outlet tip.
7-You are in Denmark. All 2008-2010 Euro spec XB models use a different header assembly with re-sized collector. Said collector not compatible with earlier year XB9 and XB12 mufflers. Be aware of that when shopping for a muffler.
That's the best I can explain it to you.