greddy kit right...? well first start the car, so your manifold isnt that hot....open the throttle and put your hands around turbo manifold. While its reving you should feel air if there is a leak. Also its easy to notice a leak by the noise... That you can do your self, or have a shop perform a leak down test. I had to order a gasket for my old greddy kit once, they use the same manifold gasket as the nissan 350Z Turbos.,,you have the Tdo4 right...? You can get these gaskets at your local nissan parts dealer, probably special order though. If you had the kit for a while, its a good possibility its the gasket, but if not lets hope you find out what the problem is soon
