[techweenie]

Marv is correct. Up to +10 HP. No more.

This particular engine year has a poor reputation in the Porsche community and does not add value to the car. Any PPI would include a torque check on all head studs. They were subject to pulling out of the case on the '75-76 engines, and to a lesser extend, '77. The primary reason was the 'smog stuff' -- specifically the thermal reactors that focused heat directly under the cylinders. Expansion and contraction of the head studs became out of sync with the rest of the engine, and they slowly pulled out of the case. The fact the thermal reactors are gone on this particular '75 is a plus, but unless a case saver solution has been applied, I'd be a bit concerned about the head studs and discount the car accordingly.

Bottom line on this is that with any of these cars, a good PPI is critical.