I think alot of the turbo/motor fade people are having is actually
battery fade!
I too have experienced this before. With timing advanced speedies, you are taking alot more mah out of the lipos and drawing heaps more current!
You will never get the same punch out of a lipo after the first 3 minutes. I thought my turbo was off, but when pulled up to test, turbo was working fine. Temps were still ok.
Try this next time. When fading, exchange your lipo for a fully charged one and you will see what I mean. Cant do that during a race however
but you get my drift!