After selling out we will be discontinuing this offering!

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Due to special requests, MRP has released some wide-mouth 100mm velocity stacks!

Quick facts:

• For 4AGE / 4A-GE AE111 Blacktop and AE101 Silvertop ITB's Only
• 100mm length
• Rolled aluminum construction
• Hand TIG welded to a custom fitted aluminum base
• Includes BGRS supplied stainless button head bolts

 

Some of the fastest teams in N2 Japan race series are using long and widemouth stacks. For most applications, you want as wide and smooth of an entrance to your velocity stack as you can get, but there are typically other considerations (such as space) that prevent the use of an extra wide entrance, like the ones featured on these stacks.  Extra machining is required to fit the stacks up nice and flush next to each other, which increases manufacturing time. 

Do these actually work? In our experience, yes!  When we have tuned cars without a very wide opening like this (and engines with competitor's stacks) and we have experienced pretty noticeable losses in high RPM power, as the tip of the stack seems to become a restriction at very high intake velocities.  So in general, you want a stack that has a wide and parabolic opening...if you don't, you may be losing up to 5-10hp at peak RPM.  

These also look pretty damn cool. 

Note:  Due to these stacks exta girth, they will not fit behind a filter an enclosed filter like we normally sell for use with velocity stacks.  So these are best to be used on a pure track or show car, where there will be few miles driven per year without proper filtration!  Also, these may not sit flush if used with ITB adapter plates onto other engines, such as 16V 4AGE, BEAMS, Miata.  Please consult with the vendor for the ITB adapters whether or not they maintain the same