I'll take a look under the car, just got the car yesterday so haven't explored the whole thing yet, but on one my first cars deleting the resonator and putting a straight pipe made a noticeable difference in sound in and out. I looked under the car earlier today, there's looks to be two mufflers, one at the back and another towards the front, I'd have to lift it up to get a better look, so I think the back one can be deleted, but don't know if it would affect performance at all. For now I'll keep my exhaust stock since I barely have any miles on mine.
I personally wouldn't do that. It's going to sound like crap. Like a cheap tin can rattling on the ground. You'll also have to slice off after the downpipe to remove the cat. Then weld on a straight pipe.
Just do a proper exhaust. Save the headaches.
My two cents only, but in many cars that I've owned and seen, I've never heard a good exhaust where all they did was remove the resonator. Sounds like garbage to me.
I have no cat and no resonator...just straight pipes from the turbo back on my 135. Sounds really good at WOT and above 2500 rpms. Anything below and it sounds like a diesel truck haha. It's fairly loud too, but I live with it b/c it's my track/fun car. For everyday driving it'd be a bit much. I wouldn't consider doing that on the FiST.