Right to get started, i have a Saph Cosworth with the following spec:

200 block
Low comp pistons
Lightened and balanced bottom end and flywheel
Ported and flowed head with BD10 cams and bronze valve guides
Kent alloy vernier pulleys
T.34 turbo with .63 housing (Turbo technics stage 3 i believe)
Green injectors
Stage 3 chip
3 bar map sensor
RS 500 intercooler
Alloy radiator with twin fans
Full mongoose ss exhaust
K&N cone with alloy trumpet
Samcos

With this, the car when last rolling roaded produced 317bhp at the wheels.

This was all done when i bought the car and am now craving more power, as it will be going off the road for winter i am keen to increase the power and hopefully see 400bhp+.

Could i have some info on what i would require on top of what i have please?

I'm thinking along the lines of bigger turbo, bigger injectors, remap anyway. Just not sure what i may not be thinking about and should be. One thing in the back of my mind is the conrods and crank, what are they capable of handling as standard as i have no indication of stronger rods.

Cheers
Scott