nice ship! heres some shotgun baking tips:
Just remember for normal bakes: seams are unavoidable. hide them. you can hide them out in the open, just as long as they run along the edges of bevels or something else that makes sense for a break in normal tangency.
UV breaks, and Smoothing group breaks = break in normal tangency which creates a seam.
Seams are good though because they reduce the amount of strain you put on those smoothing groups.
For example- if you were to put 1 single smoothing group on your low- the low would have all kinds of messed
up smoothing as a result of the smoothing not having enough geometry to accurately represent the surfaces properly. The bake from this would show all this messed up smoothing as well.
If you keep all the smoothing groups you have on the low already- and translate each one of those smoothing groups to a separate UV shell- the resulting bake should
turn out clean. (although you`ll want to thumb over your model and make sure your smoothing groups are all nice and orderly before just skipping that step altogether :P)
*edit* I though this was a spaceship too. Maybe look at Taehoons
sub for some ideas? (scroll to the bottom)