ok so here we go.... this is a resonator..
this is the inside..
And this is what it sounds like before and after you pull it out haha, which will cost you from $50-$70, its as simple as cutting it out and putting a straight 2.5" pipe in its place
Before - Mazda MPS |BEFORE| Resonator Delete - YouTube
After- Mazda MPS |AFTER| Resonator Delete - YouTube
overall its a easy little mod that yields some sounds and 0kw
i will re upload another vid once i have my dump pipe installed with a single high flow cat =P