Aftermarket mufflers do not require bending, but you may need to do some work to the pipes to make everything fit if the old one rusted off.
I haven't had a breaking issue in 4 years, unless you count when the brakes need replacing and it makes noise...
Just remember I am not a lawyer and would never recommend you remove the ABS fuse (30 amp under the hood) but I have done it and it works wonderful...