I am going to buy a RC 3 inch lift kit and probably some 31s and I want to know what I need to do to bring the xj up to optimal performance with the mods to it. I know the speedo will be off. Is there a way to fix that? Is there anything else I should do transmission wise? Thanks

 

Not with just a 3 inch and 31's

 

speedometer will be a little bit off, like 5-7mph at 65+mph

it's a cheap $25 fix.