I did this 'mod' a few weeks ago and recently started to hear chatter when coming off boost. I've got the 007p fitted so knew it couldn't be that. Had a look under the cover and found the heat had caused the vacuum pipe to fold onto itself where it comes out of the top of the DV. Managed to sort the problem out but looking to get some better quality tubing. I'm using 4mm at the moment and was wondering what difference 3mm would make, if any? What size have people used when doing this mod?