If your going to be changing the speakers in a BA. The stock front and rear speakers are already 5x7. you can build speaker adapters out of 3-4mm MDF to fit 6.5 inch speakers in the 5x7 holes. I have put 6.5 inch splits in the front of my BA and 6x9's in the rear. much easier doing the 6.5 splits. I had to make huge mounts for the 6x9's in the rear. If i changed my speakers again, i would put 6.5's all round. Much easier cleaner sound. I already have a 12inch sub running, so i don't really need the 6x9's.