You writ 420Nm is this correct ? the car alredy have 400Nm as standard.
The Danish deale for this NOS system say at some V8 in Germany has up to 200hp NOS system without any problems also for the automatic model, the NOS also give about 200+ Nm, and if the guy in Denmark tell me the true ? the V8 shuld have about 480hp and 600 Nm.

The system i have in my mind is a 125 Hp/Nm system, the car shuld then have about 410hp and 530Nm.
I also know at the kompressor install give about the same.
Are your shure about the automatic transmission can't take more than its alredy have as standard ?

Regards
Søren