Yea, JBA is one of the few manufacturers that offers a factory connection 3" to 2.75" x-pipe or a 3"-3" pipe for custom exhausts. I believe they also offer a full exhaust system that is 3" from the x-pipe all the way back to the mufflers. No need for a full 3" system though unless you're making huge amounts of power.
I don't think they make shorty h-pipes for their headers.
2014 Mustang GT 6R80, Procharger Stage 2 D1SC, BBK 85mm TB, Boss IM, Sai Li fuel system. Circle D 3C, 1-7/8" Kooks Long Tubes w/Offroad X Pipe, Lethal Over-Axle Pipes, Corsa Quad Axle-Back, Eibach Pro System Plus, BMR K member, Shaftmasters DS, Forgestar CF-5 Wheels and Nitto NT05 tires. Lund Tuned
Lots of suspension goodies and some other stuff I can't remember.