I have a 1997 Honda Civic Ex coupe it has a y7 with a 2000 y8 intake manifold and a 2000 manual transmission today I went to leave for work and noticed when accelerating it sounded like a motorcycle but when I down shift it sounds completely normal I have checked over the exhaust and haven’t found anything wrong(I don’t have any catalytic converters just a long tube header to a full exhaust out the back) I’ve checked fluids everything is fine I did however find that my intake manifold is cracked around where the coolant hose connects around the back side to around the injector any help is appreciated!