F5 BIG-IP and Imperva Integration.

A lot depends on exactly what you want the BigIP and Imperva to do. If you just want to inspect the traffic with Imperva with no expectation that the traffic stream will be modified, I would suggest using clone pools. The BigIP will mirror all the traffic it receives up to the Imperva, including responses if desired, but will otherwise go about it's normal role. I would check this out for more information:

K13392: Configuring the BIG-IP system to send traffic to an intrusion detection system (11.x - 13.x)

If you want a more interactive conversation you might try this:

https://devcentral.f5.com/articles/divert-unencrypted-traffic-through-an-ips-with-local-traffic-manager

It might not play nice with end to end encryption, though.