AT4/AT4X/Trail Boss/ZR2 are popular with the interior upgrades, paint matched bumpers and door handles (or the upgraded black bumpers AT4X/ZR2), and black trim instead of chrome. They also have an increased ride height over the other models, essentially a leveling kit with also a lift block added in the rear. The AT4 and Trail Boss still have cheap shocks and a hefty nose down rake. The AT4X and ZR2 have upgraded shocks (Multimatic DSSV) which are better but still leaving a lot of performance and ride quality on the table.