H&S deletes but with the EPA ban now the price has about doubled on them.  I run one on stock hp setting, it paid for itself in under a year just by the fuel savings from the regen cycle.  The H&S turns the EGR off, not a problem as long as you don't go turning it back to stock in a few years.  I just did the DPF delete pipe and left the cat in.  At the time it was around $1300 for everything and mileage increased nearly 25%, you won't find a new H&S minimax now for under $1500, not sure what the delete pipe have done in price.