This one is designed to cut cost  at the expense of a little
work on your part. You will have to drill the mounting holes
for your year of 13B as they vary in position. Also the mounting
flange will have to be cut in some circumstances for some years. 
Nothing you can't do with a hacksaw and a drill press.

It will fit a six port with a bit of die grinding on the ports
as well as four port turbo and a late 13B turbo. Probably the
Cosmo too.

No tricks are necessary on the mounting bolts from year to year.
It is designed to use cheap  1 1/4 and 1 1/2 inch aluminum pipe
bends from RB Wagner.
http://www.rbwagner.com/

Pipe is bigger and cheaper than tube.

What is shown are the inner parts of the runners and the flange. 
The casting itself will appear filled in around the runners.

Paul Lamar
 
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