But, you have to explain more than I do. Because the customer don't know the product well.
If I were you, I would explain as follows. Please take easilly this advice.
Please see the drawing 35160-K33A-Y502 once again.
Especially please see the harness part, there is additional process of work.
In this quotation, it takes additional time for taping because the worker have to bend the cord and tube, then keep bending the cord and then wrap the tape 3-4 times.
That's the reason for cost up.
The supplemental document is just for the reference from R&D, I guess.