well are you asking what's the part differences or what a pi swap would do to a non pi engine? honestly i don't know what gets swapped i've only helped a friend on the last part of his after the upper intake and plenum were installed (i basically just installed his chip and helped finish loose ends)...i know the basic premis is to see nice hp and tq gains due to a compression difference in the non pi motor. From what i can tell on his car it was worth the swap because when i had my '04 GT with minor bolt ons he'd leave me behind with just an exhaust and the swap done.
Here's wut done to my car and the results full p.i. Swap at 160,000 miles engine bore over 30 pi heads mild porting and plenum stock tb MAC c.a.i
Tremec tko 500 speed ford raceing alumnium drive shaft 3.73 gear runs on 91 octane sct 4 position chip with sct tune and dyno'd at 310 hp and 320 ft torque at the crank after parasidic loss 300 hp and 305/310 ft pounds to the rear wheels the p.i. Is worth it comes tax season I'm Putin in larger cams and bbk 78mm tb I've had no problems with the swap runs strong!!!!