what are the metal spacer looking things for during the install?

 

IIRC, they space the fuel rail out because of the length of the injectors.

 

^ That is correct. They are fuel rail spacers.

 

When you install the RC440's, do you have to do any mods to the fuel rail? I read the Greddy TT Instructions (They use RC440's) and it says that you have to grind down some parts of the fuel rail so it clears the lower plenum...

Is this really neccessary? Has anyone installed RC440's without having to do this?

 

You have to grind down the rail or it will not fit properly.

 

I didn't need to grind down my rail with the 650's...

 

^^Are your 650's RC? I think they're bigger than 440's right? Did you use spacers too with your stock fuel rail?