Morning Nick
Welcome to the Forum
Crazy boy !! I did read an article early this year that the tuners love the N54 engine due to it's strength and forged internals.
The article mentioned the need for colder plugs? new coils? Twin Cone air intakes? The article was talking of 400+ WHP and with the turbo's upgraded even 500 HP at that stage I think your money would be better spent on drive train and brakes
It was a US article and their budget was $1500
Good Luck
Dave