This page has info about logic-level and vanilla FETs and logiclevel IGBTs that can be used on GenBoard/VerThree.
Also FETdrivers and flyback diodes.
It is mainly for developers. Most users pick the recommended components from WebShop (but it doesn't hurt to check datasheet, of course).
We choose switches so they can bear multiple times the stress they see normally. Eg most setups have 1A per injector channel, and we recommend 10..16A FETs (which is 100 .. 256 times higher load because the currentsquare counts).
[Honeywell relays] is the temprange really -25 .. +75F ? That's not good for anything. Too bad, I really like the honeywell SZR-MY2 (2 circuits, 2*3+2 pins) and SZR-MY4 (4 circuits, 4*3+2 pins) into-PCB solderable relay sockets (there are also bigger panel-mount sockets wire connections secured by screw).