I'm killing LSU 4.2's every couple of months
.... so I will also be looking forward to this as I have 2x LSU 4.9s standing by in stock.
never ever killed it 
I am a bit frustrated that they don't last longer. They are quite dirty when I take them out, but saying that they are located a long way away from the turbos so it's at least not heat that is killing them.
I have them in the midsection of the exhaust system, and not in the downpipes, so they are basically in the OEM location.
Symptoms are that they start jumping around for a while, but then go down to Lambda 0.7x and jump around between 0.73 and 0.77.
Amy idea why they are going off so fast??