I know I have seen a few 440 dyno runs on engines making about 60 hp where the six pack was within 10 hp of the single plane and a 950 carb. On a street car the 6 pk will work pretty good if setup right as I would run one if I had a car that could have had the 6 pk option. I run this Indy dual plane intake with just an 850 DP on my 493 and I am very happy with it. With the dual plane and the DP carb it has great driveability and any rpm. I can hit it driving on the street in any gear at any rpm and it goes. Sure it may be a tad faster at the track with a single plane but this setup got me in the 10's that I was shooting for and has such good driveability that on my street car it may be giving up a tenth or so at the track but I have no complaints with the dual plane. Ron