I've got KYB's too and also noticed their pretty firm. Check close to see what is rubbing on the exhaust. Look for a shiny spot and that's a good indicator where it's rubbing. It might be a simple fix without replacing shocks. When I first put my car together the left tail pipe looked fine when I assembled it and even though I cranked down everything good and tight for some odd reason a month later it shifted a little and was rubbing on the shock. I loosened up the hangers and tweaked it a little and tightened it back down and over a year later it's still clearing fine. Go figure.