Vortech discharge sizing
Cheers
But the OD of the discharge is quite a thick casting. So ID of that and your "other" 2.5" OD pipe might not be that different really anyway.
a 90 degree 2.75" OD bend would probably be more restrictive than the 2.5" ID straight pipe
pulley to keep the piping away from the headers
Either way, all those bends even in 2.75" will be more restrictive than a straight section at 2.5"
Although they will still be more than adequate I'm sure.

