it dont matter... but if they are the street legal ones make sure the smog ports of the heads are plugged (if no smog equip is used).
EDIT: i just checked out your website and i just though id chime in on 2 minor things: (1) that red intake, isnt a cobra, its a stock explorer intake, still a nice peice tho. and the 5th cylinder runner on the lower intake, that boss needs to be tapped so you can install the stock sensor there (look at the stock lower youll kno wat i mean) (2) you dont need to use a pipe wrench to release pressure from the belt tensioner. the bolt on the pully side has reversed threads, so just put a wrench (or socket) on the bolt and turn like your loosening it (counterclockwise) and it will release the tension.. this is good to kno if you ever paint or polish the tensioner.
nice car btw.. VERY clean!