New update...

Yesterday I was thinking about the weathering on the nacelles...

 

I realized I needed to apply the pastels over the top of the darker grey area located underneath and just back of the three rectangular flux constrictors at the front of each nacelle. Looking at the kit decals, I realized they were too large to fit; they were also a shade of grey lighter than my hull color and they needed to be a darker shade of grey.

So I resolved to paint these areas instead. Using the decals as a guide (at least the rear portions where the scallops are) I cut masks out of Tamiya tape and applied them:

[ATTACH=full]51561[/ATTACH]

IMG_4943 by trekriffic, on Flickr

After more masking of surrounding areas with blue painter's tape and wax paper to prevent overspray I airbrushed a mix of Imperial Japanese Navy Sky Grey, Shady Cove, Insignia White and some of the Medium Grey mix I'd used for the end caps and impulse engines. It's sort of an intermediate color.

Here are the grey areas after unmasking and a little wetsanding to remove paint ridges at the edges:

[ATTACH=full]51562[/ATTACH]

IMG_4944 by trekriffic, on Flickr

Here's the decal showing what I meant about being oversized. Unless the intent was to cover the sides of the flux constrictors with the decal they would have needed to be trimmed to fit at the front. But that wouldn't have solved the issue with the color being too light so I think my decision to paint them on was correct:

[ATTACH=full]51563[/ATTACH]

IMG_4948 by trekriffic, on Flickr

I also did the weathering on the dorsal. You can barely see the two grey streaks between upper and lower rows of windows. The orange rust is very subtle too:

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IMG_4946 by trekriffic, on Flickr

The underside of the saucer afer weathering. I kept it very light:

[ATTACH=full]51565[/ATTACH]

IMG_4945 by trekriffic, on Flickr

I'm really trying to keep the weathering subdued, for a model this size it's really important not to overdo it.