So I removed the stock h-pipe with the six Cat looking things LOL and installed the BBK non-catted o/r x pipe. But now the sound when I'm outside the car sounds great, but while inside I need ear plugs ouch! what gives? I have a Flowmaster catback. Should I install cats and if so will the sound inside the cabin become more manageable? ALSO what type of cats should I buy etc universal or name brand.