From another forum
W2-90W Peak Power 100W
W4-120W Peak Power 135W
W6-150W Peak Power 170W
W8-170W Peak Power 195W
Tube Life: 10000hours, warrenty time:10
months
Reci have nothing on their site and I have no idea of what the improvements are - I would imagine you also need the corresponding PS , I was about to order an extra spare tube or so , think I will try one of the new ones.