I've seen a 3" IRS kit... which is the only possible thing I could see that kit fitting is the IRS. Getting 3" pipes over the axles would be really tricky tho, not saying it can't be done but I'd go dumps or sidepipes TBTH. You could always have a really good shop custom bend you something which is probably the route I'd go if you are dead set on a 3" overaxle setup.
2000 Mustang GT Steeda #0048 34k miles. 99 Cobra 4V swapped, FTBR IRS swapped, exhaust, tuned by James Gordon.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.