just about everywhere, I've read that the shocks are rubbish and should be replaced with oil shocks. And I've also only read good things about 3 racing shocks, which is why I chose them. I think they were a few bucks cheaper than tamiya's.
my only experience with rc cars is with a used tt01D that already had some upgrades when I bought it, so I don't really know much about shimming or anything.