Looking for hidden part in SL

[viper]

Yes, thats the one. And actually I found the part last night. I had been missing the part of the map where the second switch was. So every time I was not going in there. I finally studied the map and found the room where the part was, but the map didn't show how to get into there. That is until I found the second switch and found the hidden door. I think now I'm up to 74% completion with all missions done, all arena's and a rank of S. So there must be either more hidden parts or parts for doing something special. Now I'm going to go back and try to get a rank of A on all my missions. That's hard to do!