Well they are not that common, --but surely more than a 58-9 pontoon, There are multiple wrong angles on the w115-- not so much on this and wait til its done before you assume things. most of the ports on the w115 enter at an ok angle but the #1,2 th runner is a disaster for airflow #5 enters the head at a worse angle than the rest, and are a choked size to begin with. I like to make things so no fabbing required is not a big plan for me, And knowing how to weld aluminum is a plus if you are a motorhead. Remember--The w115 617 intake is NOT a 617A and it wasnt made to do that, but has been used that way. The 617 and 617a are not gassers and the plenum volume is not tuned like a gasser as you may be thinking--and if it was a turbodiesel would probaly not be the same as a N/a engine. There is no air door (throlttle body) everthing on a turbodiesel of whatever kind from the compressor housing thru whatever-a intercooler and various ducting is plenum.