X pipe H pipe or side by side

I have tested this a bunch. If you pick up with an x or h pipe you have other issues. You are adding volume. So maybe a bigger collector. Or longer collector. Or your primary pipes are too small. Like over 370 inches and using a 1.75 or 1.625 primary. That is too small.

On top of all that, if you do find a gain it is so small, and low enough in the power curve to be insignificant.

I know some stock eliminator guys are doing it. But I know one who tried all that, but when he sized the header and collector correctly, the car went slower with the high dollar x pipe.

I know for a fact, a 340 inch, 8.5:1 compression flat lifter cam, stock 73 intake and carb that picked up with when he went from 1.625 to 1.875 primaries. Then he picked up some more when he went from a three inch collector to 3.5.

When you are dealing with production chassis, you need a bigger tube header for your displacement and rpm.

Don't drink the koolaid. Save your money and put it where you can make more power. Like rocker ratio, head work and never forget to work on the intake.