axle back

Hi everyone, Few quick questions.. I have a 18’ WRX which I purchased 5k miles ago. It had a Subispeed axleback exhaust and wheels. I’ve added Cobb Big SF and AP my question is I just purchased a Cobb catted resonated J pipe and wondering if I just wait to put it on or install it this week...

Located in Arlington, VA. Paid $479 a couple years ago - muffler option adds $150 to the $329 price in the link below. Has the 4 inch muffler option which makes it sound more refined and less raspy than simply just a muffler delete. Also, the 4 inch muffler (which is actually a straight pipe...