matt...i agree with our fellow CELICAns!
the covers underneath are there for a reason.
the main reason is to keep dust and dirt from accumulating under the engine bay and around the oil pan so that when you do your oil change (like i do my own), it will not be as dirty.
just go to your local TOYO dealership and buy it there. if you have a LOWES hardware store near by, cruise on by and get them for the same cost.
as far as zip-ties...(sorry Grand-Touring-Dan)
you need to have a lot of those if you're gonna be taking out the panels every maintenance you have to do! like ISAAC said
...no one is going to look underneath your car every single time and for those who think zip-ties and twist-wires are "ghetto"...i say..."you're jealous because your brain didn't think of it".