4.0 SOHC heads

I'm a do-it-yourself guy. Right now I want to stay N/A with my car and add further power by doing heads. I've read that they are the weak link of the N/A system in the 4.0/S197 drive train. (I'm not talking about 450Hp weakness but N/A stock) They just don't breath well. What I would liek to know is, what year 4.0heads will fit this version motor? I know that this is a SOHC motor, is it different from the OHV ranger motor? Please be as technical as possible. Where can I find valves for these heads? Does anyone know of a place to by rocker arms or springs as well?
I really don't want to buy a premade head from SSM or PH, no offense to them but i want to do it myself.
Thanks in advance for the help everyone!

I own a 4.0 2006 Mustang and want to wake it up with help from experts that been doing work like this for years in the Explorer...

 

[Turdle]

I moved this one to the need for speed forum--I think you'll get answers here-

 

[rmays07]

Thanks!

 

[jah81592]

Who told you these heads are the weak link? Obviously they were meaning the OHV heads. The SOHC heads are incredible performers. The intake ports are extremely large and the exhaust ports flow exceptionally well. As far as porting goes unless you go with a stroker kit or going to run super high rpm these heads won't be signing off any time soon. I went 9.67 in the 1/8th with just bolt on's and tuning. If you are looking for valves and engine parts then go to www.supersixmotorsports.com

By the way these heads don't have rockers they have what is called cam followers and they are rollers anyway so I believe you won't be having any problems whatsoever. All the sohc heads are the same if I am not mistaken. So swapping heads from another 4.0L you will be getting the same head. The 4.0L ohv (pushrod)heads are weezers they will not bolt up to your vehicle. The ohv engine was never known for performance only really for dependability. Just food for thought the pushrod and sohc use the same crank,rods, and pistons(I won't go into major detail but here is a crash course,earlier model cranks weren't machined for the camshaft sprocket but later ohv's were) so basically the only thing different is the block and heads (obviously the sohc isn't a pushrod engine) and you are looking at a 50hp difference between the two. This should be convincing enough these heads flow well.-J