I have a pair TBI-48-4/5's, one's already installed in my rocket (not yet flying) and will be retrofitting the other to my flying RV-6 very soon (I've been saying that for the last three months ). I have made several test flights now to collect accurate "before" data. As soon as the weather here turns a bit sour and I have some time, I am going to make the swap. Stay tuned, you'll know soon enough.