Hi Paddy,
The extra 7kW is a rough estimation of the 25 - 30% loss through the drive train.
Doing the sums allowing for the 20 - 30% we get....
the 13kW = 16.25kW - 16.9Kw
the 8kW = 10kW - 10.4kW
Added together we get 26.25 - 27.3kW
Add this to the 147kW....173.25 - 174.3kW
So, my estimation was really pretty spot on as it turns out.
I understand what you are saying about the torque, if my memory serves me well without delving in to my files, the max torque comes on at 4800rpm and the max power at 6400rpm, in the standard motor, so a calculation would be hard.
Oh, and the power from the induction mods were dyno proven and the exhaust was a verbal from D&T Performance Exhausts here in Australia...they had done heaps of S15s and assured me this was what previous dyno runs had shown. It also saved me $129 to do again what they had already proven.
Just out of interest, the figures my car showed on the dyno were even better than the 20% loss. It showed 120kW (18.5% loss) without the induction mods and 133kW with. This figure, 120kW, is pretty well exactly what a lot of other dyno runs I have read about show. One I have the article on shows a stock S15 with 126.7kW ATW
Cheers,
Ron.