Does anybody know if you can order the LB7 y pipe and replace the converters on the lly. If so does it cause any code issues with the PCM. Has anyone got one from GM. Cost??

you can replace the pipe with an lb7 pipe and leave the muffler on and you'll have no codes. it would not be a y pipe as there is only one pipe with one cat. if you plan on doing it, i believe GM is around $167 and you can get one aftermarket. Mark from DPPI has an MBRP 4" pipe that will bolt right up for $124. You can shop around and yes the 4" will bolt right up to your exist 3.5" cat abck exhaust. plus it will give you a chance to change your exhaust out in the future to 4" all the way with a 4" cat back system.

if you do a search for "front pipe" you will find all the info you need. As he said above, its not a y-pipe its the front pipe. I just did this and the part number for the pipe he speaks about is GMS9401

http://dieselplace.com/forum/showthread.php?t=24848