Driving the supercharged cabrio. My car has the factory fitted JCW air intake box. Are there any aftermarket air intakes which will make the car perform better than the JCW? Alta?

Any recommendations?

My JCW box undertray seems to be missing, so the thing is dangling. And not sure how often must the air filter inside be changed?

You won't realize any performance gain from an aftermarket intake over a JCW air box.

If the lower portion of the JCW air box is missing your engine will be sucking lots of hot air :eek:

That's one of the reasons why I wanna change it. I dunno how it got lost from the previous owner.....
Any suggestions are welcome please

you can open the RPM activated cowl flap so it is open 100% of the time. this will suck in air from the window cowling giving additional cold air intake. If you do this be sure to disconnect the power supply to the airbox so the airbox will not try to open/close the flap.
You can also get a MINI Madness Hi-Flow filter. Check out their website for info about the filter and instructions on opening the cowl flap. Or check this out:
http://www.youtube.com/watch?v=1BvNEh5wD1E