What injectors have you guys been using to replace the flex fuel injectors in the 6.2 NNBS?

I have a 2013, and I'm looking to do a Procharger d1, the shop who i have been talking to is recommending the FIC 60's, would I need to run spacers with those?

I would also need the truck harness adapter too correct?

I have been told with the D1 and 60lb's with the stock d1 pulley I should make around 550whp with headers. Sound right?