Help !!!! Laguna dci problem

I have wrote on this forum before and it was great help. I now have a very noisy engine bay. As if exhaust is blowing but its not. Ive had the turbo checked out and thats ok thank god. Not very old at all the mechanic said. But never mensioned anything about the intercooler or pipe work. Ive checked all pipe work everywhere and still can't find anything loose or leaking. I had the timing bely done in December and it was only alittle will after that tis started. Could there be a link or not .