Originally Posted by goldenj
i hope the steps i have are big enough for my 582 i'll be running 1/8 mostly but i wounder what a 2 1/2 primary with a 5 inch merge collector would act like i bet too big down low(in the 1/8) and great at the big end(in the 1/4)the motor seamed real responsive with a 2 1/4 header on it last year BUT never made it to a 1/4 track or had a chance to put the steps on it to see the difference. jeff
No matter what head you are using be it 12 degree pro stock or 24 degree brodix type stuff, your engine will never like 2.5" primarys at the head under any circumstances guarantied. The 2.25 primarys stepped to 2.375 may be nice for your set up and more forgiving than it would be with 2.373 on the head with 2.5 to collector and unless you shoot tons of smack in your engine, the 5" collector is way over sized as well. There are more detramental effects to over sizing your pipes than under sizing. Remember the step is intended to enhance the top end horsepower for higher rpm usage and will not increase the bottom end power numbers, in fact they are lower than what a single diameter primary will produce.
Stay with what you have been using, The larger headder will not assure you more performance on the top in all instances.