Simple answer: hot gas flows faster. Keeping the heat shield there will help the exhaust gasses move more quickly and that means more HP. Obviously not much but why give any up?
The heat soak thing is important too. I was missing the heat shield for my O2 housing on my turbo engine and melted the driver's side fan. I had to go buy a new one and get a heat shield for the O2 housing.
Bookmarks