The gains with Long Tubes are at Higher RPMs. The Shorty Headers give you at lower RPMs. The Shorty might match up with your Mid Pipe as it is now. I also had that problem and had to buy a New mid pipe when I got my Long Tubes, but I'm never at RPMs that high to really get the Advantage. But with Shorty's, your local city driving is Fast. Unless you're at the Drag Strip, then I suggest the Shorty's to save yourself the money.
07 GT. SCT: CUSTOM TUNE by "MUSTANG SPECIALTIES". LMR: GEN2 2010 STYLE HEADLIGHTS, RAXIOM: 2010 SMOKED COYOTE TAIL LIGHTS, WHEELS: STAGGERED WHL 22X8.5F-22X10R.