Hi all, Gary, I think you may be closest as we heard hissing from the front when revved. We checked hoses etc.(even removed pipe to intercooler to check it)we decided it was probably flow noise in the i/c and looked elsewhere. We are going to make up a couple of bungs to blank off the high pressure air circuit with a tyre valve in one, pump a little air in and see if it leaks, that way will show us a leak anywhere. John K. Thanks for the idea, but we can get 2 bar of boost. Sid M./John we will keep you posted how we get on.