hi guys i have a 90 g plate 1.8 16v corrado i have been slowly doing bits to it to bring it to a reasonable level but im really stuck i have a sort of vibrating/rubbing/something but the strange thing is it will only make this noise at 3500 rpm all gears any speed now i know you will say exhaust but it is deffo not the exhaust i have removed all heat shields too to see if it was that now i dont feel it through the steering wheel or the gear stick only through the floor under my feet all wheel bearings have also been replaced any and all help would be greatfuly recieved