Got one of the DJS systems last year (1 3/4" primaries going into 2" after the Y pipe).
The primaries and Y pipe fitted fine - no bashing needed. The center box after the y pipe fit well to an extent, but the design of the piece after the center box was quite bad leaving it aiming towards the floor before the final piece including the silencer brought it back up and out the back through use of the 'S' bend.
Have attached a couple photos to show.
Ended up getting a fabricator to modify and weld the piece between the center box and the final S bend w/ silencer and now it sits perfectly up below the body.
Was lucky to have it fixed when I did as the rear piece was hanging on with the clip by about 5mm - it had rubbed on the ground a couple times and forced it backwards
I think you can see in the side on photo the lighter part where the pipe had slipped backwards
Comment from the fabricator was that if that middle piece was designed better, it would fit great. Maybe Sean can comment on whether this has been done since the last re-design? Not sure when the last re-design was?