Oh and to add to what Tonka said above, you can also eliminate with the '-' function.
Googling 'site:classicbroncos.com EFI Conversion -Explorer' will return every match for EFI Conversion that DOESN'T mention Explorer in the thread. Bear in mind, that's a pretty strong limiting factor, so use the power wisely. But sometimes your results get muddled in with other stuff, so its a nice feature to have.