RE: richen after new pipe
I agree with hyperman, but I personally wouldn't go quite that far with either needle. In fact, I wouldn't move the lsn until after the hsn is tuned, as any changes to the hsn affect the lsn. I guess the whole idea is to make sure you start out rich and lean it for the desired performance in small increments, and just be aware that your tune will have to change from the old pipe.