I'm really not trying to defend HTV's efforts, but I must say, it's funny how people complained about their decision to make the glow of the impulse section red when CBS Digital had made it orange. Now from what we've seen of the third season, CBS Digital has made it red now, too. And I don't see anyone making a fuss about it. Double standard?
The impulse engine on the 6 foot model should be orange and it still is in Season 3.
Tosk is correct that it ranged from red, pink and orange in the Season 1 and 2. CBS D chose orange as the standard colour but it again fluctuated throughout Season 2. The engine glow is red on the 4 foot and 2 foot models and always has done.