The only difference between JP and US Build bumpers is the JP build has a 2 x 2 plastic pop out where the tie down area is for when it was shipped in. (i have JP as well).
I just had my front bumper replaced with a US build and it fits fine.... it takes about 10mins to get the old off and about the same to put the new one on. you unscrew the splash guard under the car and there is a screw under the splash guard on each wheel well. One they're unscrewed pop the plastic pins that are under the hood and pull the bumper off...repeat for the new one going on.
Here is a pic...ignore the damage...lol it's now fixed. had the whole front end and roof painted.