I have the Xfactor on my 2 door and had to cut the rear lower arms down by .5" as they wouldn't adjust short enough. I had a few problems that this solved, drastically improved the bowed coils and also allowed my frame side rear track bar bracket and bolt to clear the axle bump stop and pad. Check your clearances at full bump without your springs in to ensure nothing is binding or contacting.

I'm running 20.5 lowers and 18.6 uppers, no need to modify the uppers as the double adjustable arms easily get your pinon dialed in.

 

I've had the 3.5 RK kit on my 2012 2-door for 3 years. It stretches the rear axle back an inch when adjusted properly. The springs will definitely bow until you correct the spring perch. I cut my old ones off and replaced them with a set from Artec that had the 1" adjustment built-in.

i had to replace my rear uppers last year and the new ones were 3/4" shorter than the original. RK guys said they changed the arm length, when they changed to their new joints.

You shouldn't have that much of a stretch of you're measurements are correct.