Mazda2 DE - Whiteline Rear ARB/Sway Bar

Whiteline Performance Rear Anti-Roll Bar
24mm Bar
This part is potentially the single best improvement that can be made to your Mazda2 DE.  It drastically reduces body roll improving rear grip by improving the spread of traction across the rear wheels.  The front benefits from improved initial turning.
 
If you are planning to lower your car this anti roll bar works brilliantly in tandem with both lowering springs and coilovers.