probably a stupid question but, what are PI heads or intakes?

 

Performance Improvement (PI) heads that came on mustangs with the performance package.

 

PI heads came in the 99 5.4L and up f150's and then on the 4.6L in 2000. Stands for performance improvement. Then starting in November of 2002(I think) for the 2003 model year trucks Ford added more threads to the spark plug hole to get rid of the spark plug blow out problem. So if you have a 2000 or older F150 and want to upgrade then get 2003 model year heads and intake. I don't know the casting number of the improved 2003 heads but make sure they are the improved ones if you do decide to upgrade. Hope this helps!

 

hmmm good to know... how do you know if you have the PI heads?...

 

if you have NPI heads your intake ports will be more circular than those that arent.

 

What engine do you have?

 

In 1999 ford changed both 4.6 and 5.4L engines to performance improved heads and intakes through 2003.

 

the one on the left is a NPI head and the one on the right is PI

 

Ok, Im not too sure on mine. It's a 5.4 with an aluminum intake... My 03 had a plastic one..

 

I believe somewhere on the heads there will be raised letters that say "PI"

 

If your 5.4 is a 99 or newer it has pi heads