HTTP Status Code for Larger Response 413 / 400

I am getting below error when response is larger in size, We can fix below by enabling Streaming in Apigee ( Currently out of scope as needs work at all up streams)

The error pasted below: {"Envelope":{"Body":{"Fault":{"faultcode":"soap:Server","detail":{"source":{"errorcode":"protocol.http.TooBigBody"}},"faultstring":"Body buffer overflow","faultactor":{}}},"encodingStyle":"http:\/\/schemas.xmlsoap.org\/soap\/encoding\/"}

I am planning raise fault when we get above error from downstream system. What should be HTTP Status Code ?

413 Request Entity Too Large

400 "Message: Response is large