Here's some pics of the work they did.
Invidia front section with resonators - these are about 10" long, so not very big. And I believe they were added to the first version Invidia exhaust to cut drone.
This is after welding the Magnaflow resonated X-pipe on there. It's part #11386 and designed for Mustangs/Camaro's. As you can see, it's a good deal bigger than the OEM resonators.
And what it looks like on the car. Tight fit, but it clears and it's not touching anything. It's slightly more difficult to install and remove since it's one big piece now, but on a lift no problems.
OP, sorry for the off topic. To bring it back on topic, the Invidia is a very good exhaust. What I did to it was to personalize it to me, I'm over loud cars (my FX has also been fully covered in sound deadener). Most everyone else is fine with the volume of the Invidia. The resonated X-pipe doesn't really change the tone much, it makes it smoother relative to a standard Invidia.
I can also see why the Invidia is designed the way it is. There is no other place on the exhaust to put the resonators that size (Stillen puts them behind the X-pipe). They're fitting 2 pipes in the pathway that one normally goes. We tried to remount the small resonators elsewhere and they don't fit. They also can't get bigger resonators up front since there also needs to be room/length for the X-pipe. I bought some room by combining the resonators and X-pipe into the one unit. Short of running bigger mufflers, there's not much anyone can do to make a dual quieter.