I agree with the others, I doubt there is a problem with your intake. The pro you talked to must not have much experience with small block Mopar. If the Air Gap is only good for 380 ci strokers then about half the 340's at the Mopar Nats must be using the wrong intake. They work really well. I am trying to rebuild a 340 now and trying to find a used Eddie Air Gap is thin pickings. People really like them and never take them off their car.
