It is a bunch of BS. I did it myself in roughly 4 hours and then after a week of regular driving (to let the springs settle) took it to get aligned at a performance shop. Car rides just as good or better now.
it is absolutely the 30 series side wall lol. I lowered mine 1" all around with steeda lowering springs and it looks better - but still too much of a gap for me.
I will be going with 305/35s when I swap out the tires.