Well they are loud, I mean not ears bleeding, more of send the small children crying loud. I've set off a car alarm or two.
The kit isn't bad, and GMans kit came with a dummy plate for the SET valve.
Make sure you have a nice socket set with metric allen keys. I sacraficed one allen key to be able to get the bolts out so I could use a socket on the other end.
Major issue I would say was that I had a bypass leak on the inside of the slip joint for the liner. You could feel it on the frame side of the exhaust.
I pulled the liner post install (annoying) and used Permatex Ultra Copper
http://www.permatex.com/products/Automotive/automotive_gasketing/gasket_makers/auto_Permatex_Ultra_Copper_Maximum_Temperature_RTV_Silicone_Gasket_Maker.htmto seal the bypass by coating the slip part of the liner and sliding it back in.
Other than that, it started me down the road to Stealth K&N Intakes, and BULLY FI controller, to eliminate the odd burp or three due to greater exhaust flow.
--Mike