Air Horn / Velocity Stack and Size Comparison

Extrudabody achieves good flow from an air horn design you may not be used to.  Yes, those little red anodized rings on our ITBs really do flow well (see results from an independent flow test here).  To make this point more visually, here is a comparison picture so you can better understand what's possible with our design:

The above picture shows the cross section of the tapered shape that is important to air flow. This shape is reproduced inside our 45mm Taper ITB’s not on the outside.  

You will also notice if you use a 40mm ID Base Plate and a 40mm Extension that is taper bored from 40mm to 45mm you can run our 45mm ITB’s on your old 40mm Manifolds. This gives you a true taper to the intake track before the manifold, not a carb-like choke.  

Also, the Tapered Extensions can be placed between the ITB and Horn for a 3” long taper to mimic that of a conventional horns!   What’s most important here is to not get caught up in the looks so much, but what the ITB/Horn Taper actually does. Also remember, we give you easy mounting Filters with the Horns, not leave it up to you to figure out how to filter your own engine.  

As a side note, conventional velocity stacks that fit other Companies ITB’s will fit ours as well, as we use the same 63mm/2.5” bolt pattern that they do. You just drill the mounting holes out .035” larger and bolt them up.