Does anyone know what angle bends are in the RB presilencer?
 

I need a replacement pipe made but I need to know what degree of bend the ends of the RB presilencer is. Anyone know?

The only way to make one properly is to take the car to the shop. Have them remove the silencer and make up the new pipe. No way will somebody be able to tell you the exact specifications, eg angles, lengths, flange specifications.etc. Quite a while ago I made one between the stock cat and the RB turbo back "Y". It was a real pain becuase of the acute angle.