vadersi

I have a ef hatch with ls motor and dc sports 4-2-1 header and thermal exhaust.. I want to put a cat in place of the test pipe.. ( exhaust sounds ricer need it toned down alittle + emissions)I take the test pipe out and there is only like 11 inches between the header and the thermal flange what cat to go with tryed searching by length but all sites just say what they fit no measurements...