VENDORS: Companies that I am aware of that sell sway bars for a 1.6 chassis.
Front:
20mm - Mazda
13/16" - Addco
22mm - Mazdaspeed
7/8" - Addco, BSP, Dealer Alternative, Jackson Racing
24mm - Eibach
15/16" - Racing Beat, Motorsports, PBC
1" - Pettit, Helwig, Ground Control, Suspension Techniques, Rod Millen
Note: to install the 20mm 1994+ front 'R' bar in a early Miata just drill a new hole about 3/4" in closer toward the bar bend.
Rear:
11mm - Mazda
12mm - Mazda
1/2" - Addco, Ground Control
14mm - Mazdaspeed
9/16" - Addco
15mm - Eibach
5/8" Addco, BSP, Motorsports, Racing Beat, Dealer Alternative, PBC, Jackson Racing, Rod Millen.