My oldest brother ordered a new 1972 Challenger Rallye 340 back in 71. I was just a little kid, sometime when it was fairly new, he put one of these Offy Dual Ports on his 340, they made them with the spreadbore flange so he used his Thermoquad. I just thought it was cool that he put an aluminum intake on his car. Fast forward many years-when he was freshening up the 340, he put the stock intake back on. That was when I had a chance to inspect the Dual Port. I asked him how much of a difference it made over the stock intake. He said it didn't run as good as the stock TQ intake does. Might be ok for mileage.