So I have a YXDL 6.0, the muffler i bought has dual in/out 2.5" PN 12568. One muffler shop says he will install it using stock pipes. Another shop says that muffler will not work, says only dual in/single out will work, 2.5" in/ 3" out, PN 12588. He will cut and block the rear 'Y" pipe to the...