Interesting. The build sheet for my truck indicates it originally had a wireless entry and, "fob," to run it. Long gone. Considering it age, ( GAD! - and mine too....), I've not even thought about adding an after-market keyless entry. Maybe I should???? How rough a job is that? And from where?
Plenty of players in the game and many are made by the same parent company (DEI) - Viper is a well-known one but I would avoid their top-of-the-line product that allows operation via your cell phone, as it has been hacked in the past, and I wouldn't want my access to the truck controlled by something that can so easily be broken, lost, or go dead. Fob battery lasts far longer and modern ones are rechargeable via USB cord.
Keyless entry, remote start, alarm, starter kill, and alarm pager on the remote are pretty standard features of most mid-range systems these days. Don't be fooled into thinking they will stop a real thief though; they know their way around those systems. They just slow down the amateurs. As with anything, quality of installation matters a lot. A "quickie" install where the cut-out on the starter kill, and placement of the module are easy to find, also means they are quicker to be defeated by a thief.
Richard