What is the difference, I used google, the search button on here, checked rc engineerings website, and got not real information, other than people saying to get the oem ones... that doesn't help me since I was unaware of a difference, but after buying them from a member on here, i found out very quickly they don't fit into my manifold.

 

Won't really answer you question but a lot of good general information.
http://www.injectordynamics.com/