hey all i was hoping you guys could clear up some confusion i have about the 5.4 engine. from what i understand, it has the same bore as the 4.6 block, but uses a longer stroke to obtain its displacement. i also hear that 4.6 heads will fit on it and all, but not the intake. if the block is the same since it uses a longer stroke to gain its size, then why do people need to use intake spacer to make cobra or gt intakes fit it. also i notice that some people use navigator heads. if the cobra heads fit, wouldn't you want to use them since they flow better...at least i assume they do. any and all responses to help me understand these things better will be appreciated.