look. i found an oem setup on here in a matter of minutes (i'm not affiliated).
https://www.m3post.com/forums/showthread.php?t=1591915
you could find something similar in your area and have it put on and get the car flashed back to the oem software.
then sell your "test pipes" (thats what what you have is called) and whatever rear section you have and you'll probably break even.