Boxers don't have a sound...
And if you don't want the UEL sound don't get one. Unfortunately there really isn't much out that seems to perform well enough to justify the cost for el. All of the good performing headers seem to be UEL
Also these cars are quite raspy with a el header so if you are you okay with lots of rasp you may want to keep the oem header or get a very well muffled exhaust.