Yeah thanx 'DC2fanboy.' I installed the bypass valve just behind the strut-brace (before the pipe curves into the throttle body!) So it's very short-ram cos as you stated, I was making sure hydrolock wouldn't be an issue.
But today I got a section of 3" diameter black rubber water hose, and cut it to a 4" length and used it to replace the valve. I'll just keep the valve in the car incase I get stuck out in a monsoon!!! It sounds much better again! But I think the hose has acted as a bit of a silencer to the intake noise vibrating through the aluminum pipe, cos it's still not quite as nice as it was-but it'll do, and I still have the option of replacing the valve if ever I need!