compression ratio
 

so i have been wondering somthing for a little while about the 4.6 modular motors, i used to have a 96 gt and everyone told me that by switching to PI heads and cams i would actually have more hp than a 99-04 pi motor. I chose to just sell my 96 and get into a 99 gt im definitely wayy happier inthis car than the last but i wonder about a few things...if putting PI heads an cams on a 96-98 gives it more hp. what i get out of that is a 96-98 4.6 is a higher compression ratio motor where as the 99-04' 4.6 is a lower compression motor. my question is WHY? why would ford change the compression ratio?
and could somone tell me what the compression ratios are for the 96-98 and 99-04 (yes i know i could google that but if somone knows lemme know)

The heads have a different (combustion chamber) CC so the older non pi heads had larger CC then the new 99-04 heads. So when you add the 99-04 heads to a 96 car with the smaller CC the car gains compression. They added some compression with different pistons in 94-98 2vs to make up some compression they didnt get with the larger CC of the non pi heads.

Does that make sense for ya?

yep thanks thats pretty much what i was wondering.