Why not remove the acoustic valve and carbon cannister?
I havent done it but understand there are no negative side effects.
Completely forgot to check the driver side though (doh!) and that's where the carbon canister is isn't it? So I assume that side would be harder?
Just remove arch liners.
There is a splitter that I have seen on a Clio, with bit's that could be cut out and a oblong scoop put in.