New to the game

Please can anyone HELP me. I have a 1998 uk spe turbo with the prodrive pack on. At the monment it's off road due to cam change spark plugs etc. But before i put it off road it seemed as if the engine was lacking in power and it would make a jerking sort of thing! There was also the smell of peterol coming into the car. I did notice that the pipe that run just under the radiator in the front (manifold I think?) has a whole in it? Please can anyone HELP me rectify this as I dont want to take it to a main dealer and get ripped off. If you could also mail me on celt_13@hotmail.co.uk with your answers that would be ace. Thanks people!!!!!!!