Ι have had the BMC CDA fitted on my old 1.4 101 MK4.
The performance is nice and the sound also very good.
However the BMC cda installation i see in the pics above is not the best one. It sounds weird yes but with that installation top speed was limited....
The best induction though is not the BMC.
Its an air induction kit without many bends and you have to modify a bit so that it fits the MK4 engine bay.
Most of us used the peugeot 206 induction made by SIMOTA or other brands.
Nexus Frenchs induction is alright however the performance is not the same as with the 206 induction.
You need as less bends in the piping after the induction and as short as possible.
http://www.ibizamania.gr/showthread.php?t=7532
Here is a DIY i made a few years ago...i know its in Greek but you can see many pics there.
Uploaded with
ImageShack.us
Uploaded with
ImageShack.us
http://www.youtube.com/watch?v=BJtKFqYbBBI
And another pic off a mates installation
Most of us bought this SIMOTA look alike induction as it was v v cheap!
55 eyro back then and the performance was the best from all other inductions after testing etc...