You never know, Hound's Tooth has primary thrusters pointing upwardsyeah but primary thrusters don't usually point forward.It's backwards. The artist wasn't terribly clever.
Because it is oh so easy to tell which is the front on the ship, especially since the ship is piloted and once was built exclusively for a droid. Droids don't necessarily need windows.
I'm pretty sure those are exhausts for the reactor. And the main thrusters are the horizontal lines behind the cab.
And that's the thing. Thrusters can look like anything and be placed anywhere in star wars so no wonder there's confusion on the aggressor.
Tie fighter thrusters are tiny specks on most of our models. Yet they can keep up with the rear spanning Falcon engine.