when i installed mine on my G37, at first it was loose, but not that loose...you need to keep playing around with the rubber couplings and the clamps...it will eventually tighten up...to be honest, mine had a lil bit of play after i was done...not much but it was annoying...i took a heavy duty zip tie and held it down behind the bumper...you cant see it and it gives the piece of mind that its COMPLETELY solid...
on a side note, the passenger side is VERY close to a wiring loom and its holder, try to keep it above it or keep the pipe as straight or pretty much high as possible, i noticed when ihad the pipe lower the car did not feel as it should, so i took it back off and redid it and sounded different and felt better...
