I now have both the GW header and midpipe on the car mated to the stock rear silencer.  Car is still on stands so I have only started it in the shop to check for leaks.  Install went well without any big problems.  The hardest part was to wiggle the stock header out of the engine room.  Looks like I could have saved me some time by reading the install thread on the gw forum first though...

Since I didn't read the instructions I had to get all the heat shielding off the stock header to wiggle it out. It is very well made but has some serius restrictions in the collector going into the pre CAT.  I'll make a separate post with pics of it with some measurements.

Eninge bay without header. I like the intergrated heatshielding on the manifold gasket.
I will need to add some heat shielding to the generator since I can't find the strip that came with the gw header.

Here is a pic of the gasket onto the head.  The exhaust channel is about 36mm id (1.8l )while the gasket is about 40-41mm ID.

Here is the gasket on the GW header.  The runner flange might be a restriction so I grinded it down with a dremel.

After some rough grinding:

I also did some grinding on the flange after the collector as the there is a 2mm restrictive edge on the  inside.  I'm really interested to see how the RB header looks on the inside of the flanges to see if they have smoother transitions as I'm not that impressed with how they are on the GW.

A pic of the mid-pipe flange.

The studs for the spring loaded donut-gasket-thingy needed several rounds of wd-40 before they finally came loose.

I don't like the lack of heat shielding in this picture. I would have used exhaust wrap if I didn't know that all three brands I have tried before has all failed by turning into dust in less than 6 months.

Midpipe has a nice and long resonator with no internal restrictions like I had on my NB Simons midpipe:

The hanger on the mid-pipe was way off and touched the PPF.  I had to grind of about 1cm + bend the OEM hanger on the PPF to get it to sit right. Not impressed.

Hopefully the roads are free of ice/salt in 2-3 weeks.  I'll let you know how the sound turns out and if there are any change in performance.