I'm just curious if you have a build post here or on another Jeep forum to detail your setup... your mentioning driving 80-90 MPH was what astounded me. I do alright, comfort-wise with my Metalcloak Game Changer light... but wonder if there is a magic bullet for not feeling like a white knuckle adventure when you go over 70 (or also how you do it without stopping for gas every half hour.)
I don't have a build thread but should probably make one. I wasn't joking when I said be careful about your suspension set up, lol. My buddy has a 2011 4 Runner and we have taken wheeling trips together and swapped rigs he says my jeep rides nicer on the highway than his 2" lifted 4 runner wth 33" AT's. Not ragging on 4 runners they are great dependable rigs, but I would be willing to bet those saying their jeeps ride harsh have ignored most of what I'm about to say below.... (BTW My profile on JK-Forum has most of the basics of my set up, my handle on there is Biginboca)
That being said I would say the magic bullet for pleasant handling in a JK are:
high backspacing (I have preserved exact stock scrub radius on 37 x 13.5" tires by using 4.5" backspacing, which also makes ball joints and unit bearings last much longer as well as handle better). On 35's the AEV wheels will also do this with their 5.2" backspacing. Having correct scrub radius makes the handling much more stable at speed and makes steering effort lighter at parking lot speeds.)
4.2 to 5* of castor negates flighty feeling from lifting.
Proper tire pressure (chalk test) I'm running 25 psi up front and 26 in the rear on e rated tires. Most people run too much pressure.
Long and soft progressive (or multi rate) springs vs shorter stiff ones with less coils will make for a more plush ride. (I'm using synergy 3" springs which netted me exactly 3" up front)
Slightly firmer damping on the shocks to make up for the softer coils and soak up bumps at speed (fox reservoirs in my case)
Very high roll center (I raised my rear roll center about 7" with the highest rear trackbar bracket I could find, the AEV rear tower). Most lifts only raise the roll center 4 or 5". The higher your rear Trackbar mounts (more level) the less Side to Side jarring is transferred to the jeep frame over bumps at speed.
Exactly 3" lift with a Front Draglink Flip (raises the Trackbar and Drag Link exactly 3" also). This is important because if you have exactly 3" lift and a draglink flip which raises everything 3" you are back to stock steering geometry. (i.e. A 2" lift and no draglink flip is not as desirable steering geometry, neither is a 4" lift with a 3" drag link flip.). The factory set up the steering the way they did for a reason, why not try to mimic their geometry exactly when you lift? And really a JKU should have minimum 3" lift anyway they need the belly clearance, IMO.
I'm getting about 200 miles on a tank on trips at speed 80-90 with my 2011 3.8 and manual transmission (5.13 gears), so I am stopping for gas like every 2.5 hours. I should also mention that my tank is slightly undersized too because I had to reshape it a bit and lost a little capacity. (With 12" travel shocks the rear driveshaft shifts side to Side quite a bit at full travel with the high roll center, and my Driveshaft was contacting my fuel tank until I reshaped it.)
