just wondering if we should through in some cameo characters from different series. i'm sure we can do someone from initial d, over rev, wangan midnight, etc?

Overrev for sure, Since our main is female.

no

Initial D since the story is about togue racing?

over rev is also about touge racing.

we could have some random character from initial d or over rev show up at the end of the anime and challenge Mizuki, with or without a clear winner.

or maybe we should just make a reference to some of the shows, something obvious but without clearly naming it. example: main character is going for a run down the touge, just to blow off steam because she's angry at that time. She's so angry that she takes corners way too fast, carelessly, but by some kind of miracle she never crashes. then we see her passing a white trueno or a yellow RX-7 like it was nothing. I don't know it's just an idea.

Driftking why do you say no...just wondering...

sorry, i was on my psp and i cba to type loads

i just think that it will divert from the main story a bit too much, plus, don't we want it to be different to inital d and over rev?

I think Driftking is correct.
I'd say keep it different.

that doesnt mean that we cant make references though

There's nothing wrong with that.
To use actual material/footage, it's illegal.