You can run 31's with no lift but a small one is still a better idea. I installed 31" tires on my daughters 2002 TJ last fall.
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Find a different shop if they are trying to sell you ProComp stuff.
https://www.amazon.com/gp/product/B0736ZNPQC/?tag=wranglerorg-20
I will. It was a place my buddy goes too. They told me how great the pro comp is. I will just start To dig into this. First thing is just having fun. I will probably throw the bumper on my buddy gave me. Free is a good price. Then start building around our needs as we use it.