I would recommend just going with some e-bay down pipes for the time being. You can normally pick up a set with test pipes for around $200 shipped. If you don’t want the test pipes you can just sell them off later on. The cheep 2.3” down pipes will flow better then gutted pre cats and you won’t have to worry about getting the NA cats to hook up with the j-spec down pipes. The down pipes should last you a few years and you can awales get some nicer one for SZ later down the road.