I refined the iEagle and she now boosts to about 710 and cruises at 520. I flew it out of the station so I could boosts past stuff to get a sense of the speed and it's awesome

So if you're looking for a fast ship it's a good choice. I'm going to buy another Viper III and try that as well. I'm having a sort of small-ship competition to see which emerges the winner. Courier, Viper III, iEagle and I'll get another Cobra III too so it isn't left out. They all can use the enhanced thrusters I believe.