You need Magnaflow Part# 10778 for the Y
its dual 2.5" from cats to the Y, 3" out to the muffler
after the muffler stock pipe is 2.25",
the Magnaflow CatBack (#16869) is 2.5" after the Muffler ,
..stainless, guaranteed for life with Welded on polished tips, no resonators.
I've seen the CatBack links posted here anywhere from $450-$520
search part # 16869 here and on google and ebay...
I'm pretty sure AutoAnything price matches if you'd rather deal with them.