AndyF mentioned the MSD Relays some time ago. I took a look back then and they have a nice form factor and some pretty interesting features. Holley just sent me an email saying that they have added some part #s and some of the MSD Relays are on sale (Holley owns MSD). Check out: https://www.holley.com/products/electrical/wiring_and_relays/ There are lower priced relays with less functionality and higher priced solid-state relays. See: https://www.holley.com/products/electrical/wiring_and_relays/parts/7566-4 The lower priced relays do NOT have a common input power bus. The more pricy solid-state relays like this high-current part: https://www.holley.com/products/electrical/wiring_and_relays/parts/7564-HC have a single power input bus. The solid-state relays are cool because they switch fast enough to take a PWM (Pulse Width Modulation) signal on the relay control circuit and produce a PWM output for the load side of the relay. So if you need the really fast switching of a solid-state relay, these parts are a good option. Read the .pdf instructions at the link for each part# to get more detail. Full disclosure - I haven't purchased one of these yet but I have several of these part #s on my Summit wish list.