[darrin]

presume they're referring to the cylinders and pistons, and not the heads (which fit over the cylinders) -- worth asking what's causing them to want to replace cylinders. What model car/engine do you have? Believe some piston rings are hard to source/replace.

On my 3.2 Carrera (and many other 3.2s), my rebuild was caused by worn valve guides which allowed the oil lubricating the valve train to be sucked into the combustion chamber and caused high oil consumption(quart of oil every 500 miles). The remedy was to have the heads rebuilt (valve guides replaced and valve seats reground)-- my pistons and cylinders were fine and were reused. What's your oil consumption like?

If worn rings are causing leak down problems, I'd think there'd be contaminants in the oil (from gas, etc. making its way past the rings and into the sump).