swapping heads, does it work??
 

ok, i have a 96 Gt with the 4.6, i heard that i could take heads off a 99+ and directly bolt them on and is worth like 80 hp.. is this true, i was told i need the intake too with gaskets and may have to re-route the water tube that runs through the block.. i have access to a 2000 4.6, but i dont want to get into it if it dont work.. mine just seems to be lagging in the power department and now i have a hissing noise that is resonating from the air intake.. it is in the throttle body though, any ideas????

It works!
Its about 40-50HP gain. You will only see 80hp if you already have a blower, which I assume you don't since you were talking about a lack of power. But still, 40-50hp is a hell of a bolt on. The CR will be bumped to about 10.5:1, which is perfect for a N/A engine.
While you at it, you may want to think about sending the cams out for a regrind. A guy who posts on here saw a dyno verified 15hp increase. Not bad for $300 extra bucks.
There are several websites that list all the parts you will need. Try doing a search, or maybe someone else can help you out.

I would think ATLEAST 50 and probably more like 70. You get a heads/intake which is otherwise worth 260 over 215, plus you bump the compression up quite a bit. I'd imagine this is a premium gas only affair afterwards.

But I think you either need to replace or modify the intake manifold to fit it. But as long as you have the engine pulled apart that should be too big of a deal.

thanx guys for the info, my stang has 125 k miles on it already, it is tired and time for an overhaul, i have noticed it is using oil, and i do know that the older 4.6 was good on breaking down valve seals, i work at an svt dealership, so i have a hook up on parts. pretty soon here, i will be not only swapping the heads, but also adding headers (shorties) but am confused on the "X" pipe. i like the raspy sound that bassani makes, but i hear that the Dr. Gas makes more power and does not pop.. any news??