Well to do the valve guides, the head has to come off, and with new guides the valves will have to be ground to properly seat with the new guides in place. I can't imagine not doing the valves and seats on a head that the guides are being replaced in...it's not much more work to get that done..
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.