i have some previously used RC 550's (peak and hold). i pulled out my stock injectors and they are a little different for the RC's. the RC's came with injector seals, but it looks like the injectors will sit much deeper than the stock injectors. but if i put the seals that came with the rc's AND the seals from the stock injectors on, it looks like the clearances are pretty close.

so it it fine to use both seals?

here are some pics so that you guys hopefully know what im talking about...

 

Just use the seals that came with the RC injectors. Do not put both seals on.

If you have the directions they explain this.

"The injector does not go all the way through the lower manifold seal. It sits on top of the seal. Once the fuel rail nuts are tightened, the injectors are firmly pressed against the seal. This will provide a leak proof seal in all vacuum and boost conditions.

 

so the seals on the RC's are even supposed to go into the actual manifold, just kinda sit on top?