Only AEM's comes with the hydro lock bypass valve as an optional part. The Nismo CAI for the 350Z had a bypass valve. AEM is the only other mfg I know of that uses the valve bypass for the 370Z. I have Injen CAI on both 370Z's with 30k miles and no problems with hydro lock.
Did consider AEM's bypass valve and if I lived closer to Scott's place - Vivid Racing, I would probably fork over some $$ and have him "over engineer" it.
I have a few extra Injen water repellant booties - hydro shields, if anyone is interested.
There is a thread around somewhere with mods to the Injen CAI setup.