Better to dump the stock downpipes and get some that flow better. The stockers choke the turbos too much...back pressure. Those pre-cats are not really needed for emissions. They are a pain to remove. Good luck. PB Blaster helps break the nuts lose. I used a ratchet with a pivot joint at the head, and duct taped an extension pipe on/around the handle and used another u-joint and extension to get mine out.