I like this exhaust a whole lot, great gains, sound, looks, quality and fitment. I had the same setup running WITH the cat and it sounded fantastic! I just bolted up a test pipe last night and it got to a point where I was embarrased to drive down the street because of how loud it was! It is essentially a straight pipe now on the right side.

I took it for one drive (on city streets & highway) and decided to put in the largest diameter disc. It sounds like the cat is back on. I can NOT feel any noticeable power loss, but the disc is visible in there and looks kind of odd. I'm sure once the tar from the exhaust covers it it won't be so noticeable.

UPDATE: I can't see the disc in there anymore... It just took about 2 days worth of driving for it to be engulfed in black.

 

Done: much better. The passenger tip still extends slightly longer than the driver's side, but now that they are both level, it is barely noticeable.