I had a quick look at the responses you have received so far. As Nassty said, check out Ford Forums. You have to sign up to check out the Windsor engine mod section.
Quite a few people have done what you are intending and it seems to have cost them a lot of $ and some of them seem to have idle problems (partially fixed by drilling a hole in the throttle butterfly
). When reading about peoples engine mods look at what they are not saying, people dont like to admitt that they made a poor decision to spend big dollars for an average power increase that runs like **** and nobody can tune it!
I'm sure some people get the EFI windsors to run right but dont rush in. Really do your research.
The AFR 165 heads seem to be popular but you will need bigger cam, intake manifold, throttle body, computer chip (more likely new computer), possibly bigger injectors and fuel pump. Then it still might not run too well. A cheaper option might be to purchase some 2nd hand GT40P heads. Not as good as the AFR's but you can get them a lot cheaper and they will be a big improvement on what you have. You might even be able to get Heads, Cam throttle body etc from one person.
That said. IMO the EFI motors are bastards to modify (especially fords). So the cheapest/least hassle option would probably be to buy the biggest motor you can find that will fit in your engine bay.
After many years of modify engines the cheapest option (for me) has always been.... bigger engine. Dollar for Dollar the bigger engine almost always gives you more power.
That said.....I have an EFI Windsor
