Actualily the HO has lower compression of 16:1 to allow for additional boost.Good article explaining what was done a couple of years ago. A few pages back, someone posted an article showing the differences between HO and SO. I thought it showed the HO going up to 19:1 compression. This may be how they got higher numbers in HP and torque. Does anyone know for certain if there was any other major changes to the engine/drivetrain?

