takes a long time and is very messy. much better to buy an off raod pipe imo. i've always wondered the diff between a stock hollowed mid pipe vs an off raod pipe, anyone have any numbers?
Shop I took my car to just cut the pipe right behind and then started the car and blew the insides out. Granted my cats were starting to break down a little, and there might have been a little more involved but they didn't really want to talk about it too much as I was paying because they can get fined around $2000 per cats for doing it.
I took a broom handle and knocked mine out, just make sure you blow them out real well when your done, their will be a lot of dust left and particles left in their.