Mass backing helps the kit lay and line up, and the sturdy pre-mold is pretty much dead on. Trimming the edges gets a bit tricky, but for a custom fit regardless of interior options, it needs to be that way.
One weird thing is the edges where the 2 pieces meet in the middle. The finished edge is on the front section, but is supposed to go UNDER the unfinished edge from the rear section.
(according to the vid and Ford Manual). That leaves an unfinshed, funky looking edge, which is mostly hidden under the seats and console, unless you do not have a console.
The pre-mold does not lay as well if you choose to put the finished edge from the front on top (as I did, not having a center console, it looked better), but it will still fit OK.