MrMiata, the two capacitors on each side are creating a non-polorized set. Since this is an A/C sine wave, a non-polorized capacitor is warranted. To make non-polorized caps out od polorized caps, you tie the positives together and splice the negs into the curcuit. The caps values should be the same and the result of tying them together is half the value of the polorized caps used. For example, 560uf polorized caps used makes a set of 280uf non-polorized caps. Use 4 caps to make two sets (one for each side).