Wire shielding question.

So I'm basically reworking my entire engine harness, getting rid of useless connectors, replacing wires, shortening ect. My problem is, I've searched on here but can't find a straight answer. Does the wire shielding for the CAS and MAF need to be wired into the ECU ground Pin #'s 35 & 27? Or can I just splice it into the body somewhere near the ECU? Also, would it be beneficial to pull a part the gray cable at the opposite end, pull out the shielding and ground it. Everything I read said it needs to be grounded at both ends.