Just grilling the tenderloins with a Honey, Dijon, Chili Powder glaze.
Brine is simple water, salt, some brown sugar or maple syrup, cracked pepper, etc.
I would brine them Thursday night, rinse them well, dry them, perhaps put some rub on them, then wrap them in plastic wrap until cooking them on Sunday night. Just wasn't sure about holding them that long before cooking.