Important to remember is that just because the ship is large, doesn't mean the engines will match. Actually in theory, the larger the visible engine contrail, the less efficient the engine is; you're seeing useable energy being bled off into space. It's hard to see in the image, but the ship has a series of (relatively) small thruster assemblies all the way across the back hull: a pair at the extreme edges of the "wings", a large central set of three, flanked by one each on either side of the upper engine block. Beneath this is the main engine unit, with five thrusters on top of the assembly and five below, visually blocked by the structure of the ship. You have to remember that this ship is still 5 km in length, so each of those "small" engine glows are actually several stories tall and projected several hundred meters out behind the ship.
Either way, I'm glad you like it!
PS - Happy 13th page, everybody!