You sure the DC2 one fits? Was nowhere near able to fit on an EG6, was not enough room at all between ARB, hooks and bumper. The whole box is 3-4" longer than the hatch one. Can you post a picture of it on?
Also I don't quite understand your question. "Which is better?" Which ever fits best.
Didn't realise the Ek9 ones were made with 2.5" collector as well to go with Mugen center, makes sense though. I do recall the EG6/Ek4 ones having 2" collector to fit stock system and 57mm OD piping instead of the 61mm OD on the DC2 ones, would expect the EK9 specific ones to have same as DC2. I will have to keep an eye out for a complete Ek9 Mugen system.