I don't think you're right on that one judging from what was already said about Gilliam being able to keep up with the red Vajra in episode 1 while Ozma couldn't attain that level of speed.
I think the reason why Alto isn't able to keep up with Ozma in episode 7 is because he's still 'green' and this is his first real combat. He's just having trouble adapting I think
~Bowen
Some funny and/or interesting tidbits I picked up on the net...
Dracula's Aliens Attack Romanian MIG
Biomechanical Jetfighters Closer Than We Suspect?
Iran's Homebuilt Fighter Jet Makes It's First Appearance In 'Public'
~Bowen
My thoughts exactly, especially after hearing the sound the engines of Cathy and Leon's limo and of Alto's 'brother' make. I kinda liked the sound, I have to admit
The part about Aimo I didn't guess because of the title being "Mother's Lullaby", it's actually in the short description that's given with the title...
So, I've just read (on Wikipedia for what it's worth) that we'll finally learn about the secret of Ranka's song "Aimo" in episode 14, supposedly called "Mother's Lullaby" .