When I put the Borlas on, we cut out the front resonator (and the Y behind it) behind the first Y. The pipe at that point is ~2 3/4". We put on a Flowmaster 3" to 2 1/2" reducer cone, and then welded up a Flowmaster Y, 2 1/2" to (2) 2", to the stock resonators in front of the mufflers. Where the Flowmaster Y mates to the reducer cone, we fabbed a bolt-together junction, so the exhaust can be dropped if necessary without unbolting it from the exhaust manifolds.

The sound is close to perfect as far as I'm concerned. When you're on it, you hear it, but when you're cruising, it's quiet, with no drone.