Kyuukoku Tiger (AKA Twin Cobra) maximum power level hidden?

[marco75]

I have been playing the PC Engine version of Kyuukoku Tiger on NitroGrafx 0.7 / 3DS.
I can get to the boss of Stage 5, but this is one of these Shmups where it takes a long time to power up, and when I die at certain points, I can't power up enough to deal with this boss effectively.

During the attract demo, the heli shows off the weapon at an amazing power level... the yellow shot has a homing effect, instead of the usual 4-way bullets. During the actual game, no matter how much I power up, going 3 straight stages without losing a life and grabbing every powerup, I can never reproduce this effect.

What is the maximum power level possible?

Does it make a difference wether I collect a 'S' or a color changer orb of the same color I am currently using?

Is it possible to get the yellow shot to seek the enemy target?

How do I access the option screen?

Thanks for reading!

[Despatche]

Wow, I had no idea that was added until just now. Apparently you can make it homing by holding Select while picking up the yellow changer icon, I think it works for all power levels! I don't think this port has an options menu; Tatsujin does, though.