Some nicely detailed engineering units there, I could see them being modular for easy refitting and replacement as newer versions became available.
Are the larger units part of an earlier warp drive or independent sensor clusters?
I hadn't given it that much detailed thought. My general idea was the aft underside parts (above the nacelle) were engineering systems components while those under the saucer were sensor clusters.
There's sufficient detail if you're viewing the ship from a distance, but if you get up closer, well, then I might go back and add a bit more finer detail---that's easy enough to do after the components are in place.