The gunship is too powerful. I had a fleet of 12 of those and a fleet commander parked over Bothawui in the rebel campaign. The Empire kept sending fleets of victories and acclamators but i always won and had a loss of one gunboat at most. During one attack at the end of the campaign, the empire sent 3 ISDs, 3 victories, tons of tartans, and a bunch of other stuff. I won with 6 lost gunboats. Since the boost engine ability has no cooldown or timer, i just turn it on, zoom past the fleet to the back where the engines are, and blast their engines off,when they turn, move to the top of the map and repeat to find their weak spots. The concussion missles blow off hardpoints even though the shields are up. If the ISD tractor beams you, just blow it off and move on. The gunboat easily decimates fighters, bombers, and tartans, (i like seeing the giant red blobs on the radar when hoards of fighters die!). Capitals and frigates take time, but sooner or later, theyre gone...
Comments?

The lack of a timer on the Power to Engines ability in EaW seems to be an oversight or a bug, as it's fixed in FoC (they actually quite literally forgot to give it timer behavior for EaW).

i think rebels artillery and infantry are overpowered but in space empire is more powerfull

Actually, if you bother to play on higher difficulties, it's not really over-powered.