Walker Exhaust 55204 Exhaust Pipe | Frugal Mechanic
thats a list of Y pipes for sale, if you plan on changing the mufflers later, you'll need to get them off and on easy like, welded will be costly in the long run. as your paying two times for the same job.
id get the new Y pipe, a glass pack, get a flange from the local muffler shop, have them weld it on the glass pack. then go home and put your new cat back in. call the glass pack 50 bucks, the flange cost me 10 bucks, and then another 15 i think i paid to have it welded on. so for under 200 you could have a new cat back because you have the mufflers already.
this way you can work on it yourself in the future. takes nothing to drop these exhaust systems.