I just had the 15840 Magnaflow catback (dual rear exit) installed on my truck. I really like the Magnaflow sound, and quotes I got for a custom mandrel bent stainless system were almost double what I paid for the kit. I like it, good tone, not too loud until you put your foot in it, slight drone at highway speeds but not too bad.
I didn't like the look of the included Magnaflow tips, so I had some different tips put on (which means the Magnaflow tips are available, I suppose I'll post in the for sale section, and put them on ebay). For good measure, I also had the BSER rollpan notched so that the tips could be recessed a bit. All in all, very pleased with the look and sound.