yeah you're in between a rock and a hard place.

your car would benefit immensely from a FULL exhaust upgrade, but if I were in your shoes, I would source a 98+ JDM ITR exhaust from the 4-1 header/CAT/Catback which is all 2.5" mandrel bent. plus it'll be quiet, and flow about as good or better (which is likely) than what you're currently running anyway.

as far as the competitor's parts, I wouldnt bother, since this is the perfect time for you to upgrade the size. given that there are pretty much only a handful of specialized exhausts for F/I (greddy, apex, "trd", vibrant, etc) with bigger piping, you're still going to be stuck with the rest of your DC/stock cat setup.

in the interim, I would just get a stock ITR catback from a JDM parts supplier, or contact our sponsor at www.weaksauce.org