Just played around a bit with the script.
If you like, copy this into the particle.cfg:
$Type: Ship
$Class: GTC Leviathan
+Name: TestEffect
+Effect: capflash
+Time: 3.5
+Emitstate: 1
+Number: 30
+Speed: 130, 180
+Size: 1.5
+Box Min: 0, 0, 0
+Box Max: 0, 0, 0
+Spewcone: 90, 90, 90
+FPS: 3
+Creation raycast: YES
+Raycast retries: 5
+Trail: GenericTrail
$Type: Ship
$Class: GTCv Deimos
+Name: TestEffect
+Effect: capflash
+Time: 3
+Emitstate: 1
+Number: 30
+Speed: 150, 200
+Size: 1.5
+Box Min: 0, 0, 0
+Box Max: 0, 0, 0
+Spewcone: 90, 90, 90
+FPS: 3
+Creation raycast: YES
+Raycast retries: 5
+Trail: GenericTrail
Overwrite the GenericTrail with this:
$Type: ParticleTrail
$Name: GenericTrail
+Effect: Particlesmoke01
+Size: 170
+Delay: 0
+Time: 4.5
+Density: 0.9
Looks pretty nice to me. A good mission to test is "the sixth wonder" for example. Have fun.
BTW i tried to get a good looking particle trail for fighter-explosions, but the right entrys are difficult to find and it seems, that they appear only randomly. Any ideas?