Well the LS6 manifold has been installed but after also installing the LS6 injectors, I was advised to wait until it gets a tune otherwise they'd run too rich, so the LS1 injectors went back in.
I think the seat-of-the-pants-o-meter has picked up some improvement in the top end just by changing the manifold.
I ported the entry to manifold as well as spare throttle body which required me to make up a new 78mm throttle blade as the factory size is 75mm. I haven't installed this bigger throttle body yet.
I really need to get a wheel alignment and check out everything to do with the rear end handling. At speed the rear end feels very soft and I don't mean just because its accelerating hard. Almost like if you were used to having a rear sway bar, then you removed it, kind of sloppy. This makes it very figity at high speeds. I want to get a BRE rear spoiler one day to hold a the back down a little too but in the mean time I might look at the mostache bar or something, see what sort of condition those rubbers are in.