http://www.venairsport.co.uk/product_info.php?cPath=49_78&products_id=127
you need one of these mate. Highly recommend you get a cold air feed, otherwise the BMC CDA will have an adverse effect other than a nice noise! You'll need to remove to acoustic valve which is 30 min job for a novice!
taken from
http://www.cliosport.net/forum/showthread.php?t=179814&highlight=removing+acoustic+valve
* Remove (entirely) the air box, disconnecting both air feeds (one to the right and one directly under). Air box is held in place by two screws and jublie clips
* Jack the car up under front left, ensure you use a axle stand or similar
* Remove wheel, place neatly elsewhere
* Remove the underside arch-liner, fastened by a few torque screws and some fat looking plastic plugs (these just pull out with a tug)
* Watch for the small ribbed cable (battery acid overflow pipe) as its connected to the arch liner. Let this dangle somewhere.
* You will now have exposed the underside of your front bumper, note the bracket holding both your horn and the
acoustic valve.
* Try to unclip as many of the wiring looms to both the horn and the
valve, let these looms dangle somewhere
* Undo the bolt holding the bracket in place
* Tuck the horn assembly somewhere out of the way
* Remove the small air feed, no 1, simply turn it to unclip
* Remove accoustic
valve by pulling it downwards and out of the wheel arch, if you meet resistance check looms are disconnected and path is clear
* You should be left with a large gap / hole
* Accoustic
valve will be connected to a thin black tube, remove as much of the connecting bits, leaving just the tube.
This must be blocked off (or you will idle above 1000rpm) with a screw / bung similar
Tape the screw in place
* Remount the horn, reconnect horn wiring loom to horn, screw bracket back into place
* Tape up all looms and cover ends with tape
* Tape blocked pipe somewhere
* Once the
valve is removed make any modifications you wish, i.e place your airfeeds etc
* Reconnect the battery overflow pipe to the grilled bottom of the arch liner
* Replace arch liner, fix with plugs and screws
* Put wheel back on, ensure wheel is flush to brake when placing nuts or you will mark your wheels
* Lower car
* Connect new air feeds to air box, replace air box, ensure jubile clips are tight
* Job done, admire your work.