How fast can I go with 2S ? (a bit faster)

Top speed on that flight 145 kph or 90mph.
Only use about 220W total at max speed.
vTx overheat without enough airflow, limiting flight to 2 mins max.

Quad layout from top to bottom :
Glassfiber canopy (12.5cm or about 5 inches)
Caddx WalkSnail lite 1S vTx & cam
Home made balsa-carbonfiber internal vertical frame
Dogcom 2S-560mAh/150C battery
Nano GPS
ParallaxFPV TooThpikFrITE 2.5 inch frame (96mm mTm)
Flywoo GOKU F405 HD ELRS AIO V2 flight controller
BetaFPV 1102-13500KV motors
Gemfan 45mm tri-blade props
All Up Weight = 88gr

[AndrewShaidurov]

Very nice 👍
A suggestion:
Look at pitch angle at 140kph - 60-70deg I reckon, no need for rocket style shell, for an inspiration take a look at first DJI FPV drone.