Iridium is a very hard, brittle material. Re-gapping (you should check, though) is not recommended as you may create cracks or actual breakage, now or sometime after installation.
0.54 is a fairly large gap for a modern OEM recommendation, but it's not out of the realm of practicality ... an electronic ignition in good condition should be able to cross about 0.60 with typical street vehicle compression ratios and maximum RPMs. On the other hand 0.40 is not "too close" ... the plugs will work fine with that gap, again with any modern electronic ignition.
There are advantages to having as wide a gap as possible, but then again there is a line where you start to get misfires. Unless you have a highly tuned high compression race motor, the added value of that extra 0.14" isn't critical (it un-shrouds the spark a little, which in theory makes it easier to light the charge, but if you're not misfiring, which you should notice as roughness, it's lighting the charge just fine).
Use the pre-gapped plugs and stop worrying. Your car will probably be just fine with it.
If you happen to be running a points-style mechanical ignition ... rare, these days; even Big 3 motors have had electronic ignition since the 1970s as standard ... then maybe 0.32 might be more to the engine's liking. Or the other option is magneto ignition, again rare unless a purpose-built race engine, likes a big gap but will misfire at lower RPMs, where the engine's purpose isn't relevant (such as drag racing) or it's done for style reasons (hot rods, custom big motor / super-lightweight motorcycles). Neither is likely to apply to you, or anyone for that matter who doesn't know exactly which gap they want to run.