Based on my own experience I agree with Fred. It will be more expensive (two vaporsats and a 2 stage Maxitrol gas gauge) than the quote you received from Peerless for the lower firing unit but you will recover that from the efficiency of the new set-up and you don't have to move the header. One other thing you may want to get is a low pressure gauge 0 - 15 oz./in2. The Maxitrol valve is adjustable and is not set to go to 60% at downfire. When installling my unit I watched the low pressure gauge and adjusted the flow to where I now run at 1.5 oz/in2. After watching the sysyem response to the adjustments I set the first vaporstat to cut-out at 7 oz. and then trigger the Maxitrol gauge to drop to the lower feed rate. I kept records for a while basicly comparing my prior and current useage based on heating degree days. By my estimate I am saving just over 20% on my monthly gas bill. So after 4 months your expenses should be covered by reduced gas consumption.