hmmm, ya you need backflow, not sure what motor is on there or what you are putting the ORY on, but on my 5.3L the true duals seem to have a little less tourque than the 3" to one muffler, but the duals scream up top and the truck really pulls.
1999 GMC Sierra SLE ECSB .... 5.3L w/ Slight Performance Tune / True Duals with Flo Pro Glass Packs.
Project ''Bad Company'' Future = 6.0L (Forged Internals) / Boost (TVS) / 4L65E LvL 5 / AWD Conversion / Full LT's with Cats / Methanol Injection / Lowered 2" / SS Rims / Frame Up resto
Officially Employed!!!