I'm going to order an offroad downpipe tonight. There are no emissions or anything like that, that i have to pass where i live. Anywho, question is, do i need an o2 simulator if i'm not going to get my pcm reprogrammed just yet? Also, what is the cheapest place you guys know of for buying my dp? I was assuming zzp. Finally, on a scale of 1-10, how hard is it going to be for me to get it on without any leaks? Thanks!