Use powerstrokehelp.com and any other website, including forums like this, with your common sense. If you are not mechanically inclined, then why are you working on your own truck anyway? People need to know what their limits are, especially when it comes to heavy trucks that can kill someone if you repair it wrong. I wouldn't pay for any website, but I have watched all of Hewitt's free videos and I have taken from them what I can positively conclude as being right. You can get some good info on there.
I have seen many websites selling products claiming things that simply do not do what they say they are going to do. Many mods done to powerstrokes are completely unnecessary. This is a 6.4 thread so that is all I will say here. Just be smart people.