Not sure about the best looking Ninja but I do love them. (I am restoring an 1988 model at the mo)
Yours looks sweet! Slight detuning in that model in exhausts. Might be some in airbox but can't remember. My model was detuned with small carbs and intake of airbox. Got a Tranzac 4 into 1 getting made for mine currently.

Got rid of all detuning.
Really hard to get info on them. There is a GPZ900R forum (paid subscription) but have found it pretty hopeless. Asked two racers from the period who raced
them in the mid 80s earlier this week what are the cool mods. Couldn't answer as they were production racers and bikes were stock.

2 X ZRX1200R 4 X ER6N, GT550, 1988 ZX-10, 4 X GPZ250R, 4 X GPZ900R and GPZ750R

Yeah I like Kawasakis.