Who says those big things are rockets, Terradyhne?
Anyway, the NXG(and other races) do not use warp. Their method of FTL travel is by folding space and making a quick jump through a wormhole to their destination. I know it looks like they have giant rockets on the back, and honestly, that's what they're supposed to look like, but it's not what they're supposed to be. I guess that's just me turning viewers' expectations on their sides.
Since people have inquired about the other races in this universe, I decided to post some random models from it I have been working on for awhile.
http://www.villagephotos.com/pubbrowse.asp?selected=677644This first one is a Sree Dreadnought. The Sree are a small reptilian species not unlike a cross between terrestrial snakes and skinks. They average about 4 feet in length and are fantastic climbers. They are an extremely proud race but also very xenophobic due to bad experiences with a neighboring species, the Nahan, in their early space travel days. They are forced into an easy alliance with Humans when the odds become incredibly stacked against them in the great war.
http://www.villagephotos.com/pubbrowse.asp?selected=677645This second one is a Sree Supercarrier. For those wondering what this vessel is, think of the Mothership from Homeworld or the Seltorian Hiveship, and you'll have a good sense of what this ship's function is. It was designed early on the be the flagship for the core Sree defense fleets, and is a highly efficient shipyard in addition to being a powerful command ship.
http://www.villagephotos.com/pubbrowse.asp?selected=677639This is the last one for now. This is the United Earth Interstellar Defense Force(UEIDF) Titan-class dreadnought. The Titan, while smaller than most other races' Dreadnoughts, packs a devastating punch for its size. It is bristling with mass driver guns, missile launchers, and laser turrets, carries 5 ultra-heavy "Blitzkrieg" missiles, and mounts the terrifying Siege Cannon(the GIANT gun barrel built into the ship's centerline). It also carries a small squadron of F-24 "Peregrine" superiority fighters to augment its defenses. Among the enemies of humanity, the Titan is very much known and feared. As you can probably tell, this particular model is WAY too high-poly for SFC. I'm planning on doing a SFC version someday, as I'm really fond of this ship. Anyway, I hope you guys enjoyed this small further glimpse into my little sci-fi universe.