ignition, plugs, wires, etc.

hey, i know this is a bit remedial, but can i improve power/quality of idle and ride with certain plugs, wires, and ignition? as ive seen, many people get 9mm, would this improve anything on a stock 95 (or any stock in general)? also, i know that in performance boat engines (chevy big blocks) changing the plugs with deeper ones or ones made of different material makes the difference, so does the gap. are there better plugs/ gap than what pepboys/autozone has listed as stock fit? would a higher current/woltage ignition or coil be an imrovement, or is this better for racing motors? thanks.