Ok, I know the offroad pipe will give me more power than a hi-flow cat. I also know that you guys will just tell me to get a race header but come on, I live in Cali. I really want the offroad pipe but I don't want to purchase both the highflow cat and just use the offroad pipe for when I go to the track. So I was wondering if with a full exhaust set-up I could just use the stock cat. I know it would bottlneck but it would be cheaper than spending another $250-$300. My question is: Is it difficult to replace the stock cat with the offroad pipe and put the stock cat back on when I'm done using the offroad pipe? I don't want to be under my car for like 3 hours each time I do this so I was just wondering. If it is really difficult then I will just buy a high flow cat. Thanks for the information.