I could see a difference if I was talking about different years, but let's take one specific year... 1985.
This
pelican page lists the following:
83 - 86 = 150@5500
87 - 88 = 158@5900
While this
other Pelican page lists the 1985.5 as 143 hp@5500 RPM.
Finally, the
Porsche site lists the 1985 as 150@5800.
All the same year, no agreement. And a discrepancy between two document right here on PP.