I'm just doodling while I am on a conference call, but I'd love to try something like this
Basically, when I had my abarth, the stock exhaust had dissimilar lengths (and as a result dissimilar pressure) between the two exhaust outlets. When I made a new rear section so that they were even, it lost a lot of it's rumble. It got louder, but it lost "texture". I'd like to try something like the above where we'd get unevenly timed exhaust pulses between the two tips to see if it made the ST more "abarth-y".
Absolutely not ideal for performance, but I'd be curious to see how it sounds. Could probably emulate it by taking a straight-piped car and fitting a length of pipe over one of the tips and seeing if it gives the growly sound I miss so much. If I can't have my Abarth sound back, I'm unlikely to bother with exhaust for the FiST.