my friend has a 540i and wants to get the resonator taken out but doesnt know the first thing about how to go about it. so i have a few questions
1. I know its a huge thing, so what do you put in place of it once you take it out
2. do you even replace it or do you like empty out the stuff?
3. If you do take the stock resonator out (where do you buy aftermarket ones).
4. please forgive me sounding like an idiot, im sure there will be some guy laughing at his computer screen once he reads the questions LOL.

I laugh at most of the questions here. And laughed at yours too. You can take out any resonator out of any car and just replace it with a pipe. Some cars you should go to a muffler shop that is good at fabricating pipes to fit. A lot of aftermarket mufflers say you have to use their resonator with the muffler for best results. Usually the best results is to make the sound sound cool The stock BMW exhaust stuff is Heeeavy... And gong with a lifetime warranty stainless steel system is good for the car since it will weigh a lot less, The downside is most aftermarket stuff does not last and you have to do warranty claims over and over..

when you cut the old one out you put a strait pipe in place of it