Hi i had exactly the same problems as u have described, when I fitted my GTT INDUCTION KIT it rattled so I released the jubilee clip holding the silicone inlet pipe and gently slid it as if I was going to take it off and the more it moves the further away the filter dropped away from the plastic bulkhead, so it is just on the same width as the jubilee clip so that has lowered it down slightly! I then filled a section out of the lip coming down that holds the bonnet seal using a half round file where the filter sits closely but in doing that I realised that the ring around the filter that's got the springs holding it is touching the torque screw that holds the windscreen wiper surround, put your fingers under and u will feel the plastic round block that the screw goes into so i cut it in half from the engine bay using a hacksaw blade in my hand it goes through easy cos it's plastic plastic but then u hit the screw so keep going through and it will leave plenty for the screw to hold the trim! So that's stopped my rattle and Knocking noise! Now the lack in power should sort itself out cos when I first put my induction on it I thought it had lost its initial power but I beat it around for a while! And it either sorted itself out and adjusted itself out through the sudden lean running or I've got used to it? But it flies now and sounds lovely! Regards Billy