Pete's right, I'd say its more the hot air being the problem. I fitted the bmc and noticed a definate improvement directly after fitting, backed up by the improved RR figures. When I first fitted it I didn't fit a jubilee clip to hold the cold air feed onto the end of the filter canister and it soon slipped off, not only did the sound it produced change, but also the performance faltered, not alot granted because the air was still being forced up the cold air feed to the filter, but hotter air was being sucked in because there was a gap. The best thing you can do is produce/procure a pipe whic