I have it on reliable information that the Stillen exhaust on a 2009 370 with an uprev in the UK will achieve some 345bhp at the fly (310bhp at the wheels) Not sure how much the intakes might add but 350bhp at the fly seems doable.
But of course with the inflated fuel costs around an uprev will improve mpg as the standard cars run unnecessarily rich, which is an important factor.
All dependent though on the most essential ingredients - what the thing resting on your neck tells the thing at the bottom of your right leg to do