If I buy an LSD from the tuning parts menu and not the tune menu it will let me. It's still bugged though (I think) the LSD is there and you can tune it but the ayc gets adjusted too. But with the LSD installed the ayc's numerical value is changed to the LSD. It become adjustable from 5-60. Whichever you adjust last is what will stay adjusted. I hate the way the ayc makes my cars feel, so after I buy the LSD I pretend the ayc isn't there.