304 stainless is far superior to 409 SS in just about every way. Not only will it instantaneously produce surface rust, but it will severely corrode if you are in a winter weather climate like we are. The materials are also likely sourced from overseas. Whereas, all of our exhaust products are made right here in the US with only premium 304SS!
As for the modification question, the only part of our exhaust solution that requires action other than bolting it on is the catback. The new shape of the bumper's beauty panel requires action.
There are 2 options like I said earlier. The "tips" that are located in the beauty panel of the bumper pop out and you can route the round tips through the rhombus shaped opening in the bumper. The Beauty panel even pops right back into place!