It will definitely help, but a street engine just doesn't like the large ports. Think of it this way. Think of water flowing through a one inch pipe is equivalent to an engine running smooth. If the same amount of water flowing through a two inch pipe, there is dead space (the water of a one inch pipe doesn't fill a two inch part, so this would be dead space), so what happens with the water in the two inch pipe? On a street engine it becomes unstable, stalls, flashes, doesn't do as good as you want, no amount of porting is going to work at low rpm. At the same time, high rpm is great because the port fills whatever the engine can pull, but on the street, there are more guys that don't understand porting that say they won't buy another ported head because they had ported race heads for the street and they suck. With this in mind, 440 Source and Edelbrock aluminum heads flowing he way they do at .600 inch means you can suck all the air at rpm you want to that lelvel without a problem, and the larger cubes simply pulls harder through the ports at lower rpm (its a volume suction thing, nothing more), and they will still produce power to redline, larger ports simply produce more power, but unless you run at that high rpm during racing, you wouldn't know how much more power could be made (out of safety really), so, the 440 Source heads with the ports simply improved from the sand casting to the carbide burr cutting surface will improve the flow characteristics by being able to suspend the fuel in the air better, and then the location you want to make the real power is in the combustion chamber. Case in point, I was reading a comparison of seven aftermarket and stock LS6 heads,(stock comparison, ported stock, then five aftermarket ported heads). Flow was from like 280cfm stock through 385cfm ported, and when it was all said and done, all dyno'd, the difference over stock was not greater than 50hp over stock (everything else being the same block and intake). At this point, there is around 75-100hp/lb-ft torque lost through the burn inside the combustion chamber itself. I proved this on a dyno simply porting the heads and intake for a 4.9 Cadillac engine, dyno sheet proved it, other ported 4.9 Cadillac engines never came close to the numbers I produced through combustion chamber porting. If the guy didn't have the dyno sheets, a guy that had been professionally trying to build this engine never would have believed the numbers we ended up with. Statistically, the 4.9 runs 275lb-ft torque at the flywheel, I got 349.7 at the rear wheels with porting and combustion chamber porting (this is where the most power is lost on most stock heads, but I will say, the 906/452 and similar open chamber combustion heads have very little work to make slight improvements, it is the lack of compression that keeps them down on power)..