I've been traveling up to the Mammoth Lakes area almost every year since I bought the Liberty in 2001. Big Bear too. Big Bear City sits about 7k and the upper Owens river near Mammoth is between 8000 and 9000 feet. I haven't noticed any real difference in performance. I think that the electronic ignition, fuel injection and sensors automatically adjusts for thinner air.

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2002 Liberty Limited
2.5" Rusty's Coil Lift + OME 927 springs + 1/4" spacers
265x70 Revos
Warn 4x Floods
ARB bumper
TeraFlex extended front bumpstops
Rock Lizard Skink Super Sliders
Bosch Size 86 battery
Jeepin by Al's 4.5 UC Arms
Kryptonite Differential Cover
JBA Bolt on KJ Tri-Angulated 4 Link

I have been up and down Mt. Washington 2x. Once in a car and once in a gmc truck. On the way down there were several spots where I had to put the a/t in 1st gear to get enough engine breaking to minimize stepping on the brakes. But it was a piece of cake. I never overheated tranny or brakes. There are a lot of overlooks to stop on the road. Stop and enjoy the view. you will love it. The KJ will be fine......Enjoy.

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05 BLACK KJ - 42RLE & NP242
Skids, Hooks, Bent Rock Rail, Lifted, A/T's, etc.
NY and PA and Florida ONF Special Custom Organic Trail Rash