So I haven't had the time to start the fiberglass enclose but I was able to install some Dynamat in the rear.
Just a couple small pieces on the driver side to dampen out the stray bass and road noise:
On the passenger side I used a lot more Dynmat since the enclosure will fill this cavity:
Last week end some more performance mods arrived, fist an aFe silver bullet throttle body spacer:
And also a aFe stage two cold air intake:
I hear the throttle body spacer doesn't really help performance at all, I think it does cut down on intake whistle though. The CAI sounds pretty cool and it really opened up the upper RPM range, seems like it hurt the off-the-line performance a little.
To fix this I decided to get a Underdog Racing Development MAF Sensor calibration unit. Since I live in Cali I wired the box using bullet connectors so I can easily disconnect it for smog:
Then a found a nice little spot for it in the passenger kick panel:
This truck now has awesome throttle response and the upper end is screaming all the way to 5k! This unit really rounded out the exhaust and intake mods, best performance upgrade so far!