I didn't either, I used the straight inlet/outlet cats, and got them up in the tunnel so nothing hits. I skipped the flex pipes, and so far haven't had any clanging or banging from underneath. I gotta get some pictures and put em in my own thread and stop hijacking yours!
Update on this thread....after replacing the passenger side flex pipe in March, I have had zero codes for O2 sensors. My guess is the braiding in the cat was diminishing the exhaust flow, causing the inefficiency codes.
Last week, I had to have the drivers side flex replaced as it was blown up from the inside out. No issues with codes on the drivers side O2 sensors either.
Any chance we could use the first gen system from the manifold down ?
You could (in theory) use an entire 1G setup, but there are some issues you would have to overcome. First, the converter, you would have to go from a dual in - single out to at the very least a dual in - dual out w/ O2 sensor bungs on each outlet. IMO, much easier to go with single in - single out converters. Secondly, I don't know how the rear of the system (going around the gas tank and such) differs if any from the 2G design. Might need some tweaking through there.
With those two things said, IMO it is best to go the route I did...
2004 "SRT Design" 300M Special
14.627 @ 91.98 (11/23/2008)
No matter where you go, there you are.... COTM Winner February 2008, and January 2011!!