RE: richen after new pipe
I would start it up and then right after you start it up then richen it up. I would go maybe 1/2 to at the most 1 full turn on the hsn and maybe a 1/4 to 1/2 on the lsn. But no further then those incriminates. It's better to start off and richen it up right away and be a little sluggish then to start it up and hurt your engine right away and rob your engine of power and of it's life span.
But's thats just how i would do it and in the end it's up to you