2006-2007 GM 6.6L DURAMAX MBRP 4" XP SERIES CAT-BACK EXHAUST SYSTEM S6012409 2006-2007 GM 6.6L DURAMAX (ALL CREW & EXT. CABS) The Best Systems Start with the Best MaterialsMBRP's XP Series is the performance exhaust of choice for the enthusiast who needs a system that can take anything that the road throws at it. This... MSRP: Was: Now: $624.99 Add to Cart The item has been added