A 15% driveline loss is average for a Honda. This is one of the benifits of FWD verse RWD. The average RWD car looses 30% to 35%. As for whp I have seen ratings from 135whp to 147whp for the Si and from 145whp to 155 for the GSR. The stock hp and torque rating of a engine is highly subjective and is based on a 'reference' engine. A production engine is based on the 'reference' design but the hp and torque ratings of a production engine are often more or less than the 'reference' engine.