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Some OE parts look passable and others miss the mark. In the case of the factory post MAF hose, the quicker you can get it out of your bay, the better. We’ve now got you covered with The GrimmSpeed Post MAF Hose Kit that not only looks better, but fixes the flaws of its OE counter part.

Our hose construction improves flow with 2 main features:

The first is the smooth inner surface, removing the pockets from the OE corrugated folds. These folds are necessary for the factory rubber design for flexibility during installation and structural integrity. The Grimmspeed hose is made with reinforced silicone, which is flexible, but has strong structural properties that enable us to have a hose that is very easy to install without worrying about collapsing under vacuum.

The second feature is a tapered center portion, making sure the inner diameter matches the OEM air box and turbo inlet. A mis-matched diameter creates steps, which will interrupt the air flow trajectories and create small vortexes in the post-MAF hose. The Grimmspeed hose was designed specifically to prevent these issues:

Coupled with The GrimmSpeed DRY-CON Panel Air Filter, this will be the best way to maximize your factory intake system until it’s time to upgrade into a full GrimmSpeed Intake.

Note: If you’ve got a 2015-17 STI with the factory sound generator tube and want to delete that piece, you can either purchase the 15-17 post MAF hose and GrimmSpeed Sound Plug Delete, or opt for the 18+ STI hose to eliminate the sound tube provision altogether.

Testing

The first step in improving on an existing part is to find its shortcomings. The OEM rubber hose, designed with the corrugated folds, requires a straight section in the middle, which means sharper curves on both ends. This contributes to uneven air flow through the hose with high and low pressure spots. The GrimmSpeed hose design can support a minimal curve transition, maximizing air flow. The plot below shows the pressure through the length of the hose, the GrimmSpeed design resulting in a smoother transition from the air box into the turbo inlet:

postmafhose-slidesoem-vs-grimmspeed.jpg

The removal of the corrugated folds also adds a significant reduction in vorticity (a calculation used for flow disruption, with blue representing consistent flow and red more turbulent) between the two designs. Smoother flow will give us a more consistent air supply to the turbo:

postmafhose-slidesoem-vs-grimmspeed-flow-rate.jpg

The tapered center portion is also an important design choice for contributing to even flow through the hose. A plot comparison showing vorticity between a non-tapered version and Grimmspeed’s tapered hose shows an additional reduction in turbulence through the center of the hose where a majority of air flow will occur:

postmafhose-slidesoem-vs-grimmspeed-flow-rate-copy.jpg

Quick Specs

  • 4-Ply Reinforced Silicone- Extremely durable avail. in red or black
  • OEM fitment- Easy install, no modification or tuning required
  • Seamless Flow- CAD optimized design
  • High Quality Breeze Hose Clamps Included
  • GrimmSpeed Logo to Represent your Favorite Brand!

Fitments

  • 02-07 WRX/STI
  • 08-14 WRX/STI
  • 18+STI

With multiple distribution centers across the nation, we strive to provide the best and fastest shipping solution for your orders. Most in stock items will be shipped within 1-2 business days unless it is being shipped from manufactuer directly. Stock information on the website might be delayed/inaccurate, please click the help button at the bottom of the page for the most up-to-date information.

 

Carriers

JDMuscle ships via multiple carriers such as FedEx, UPS, USPS, and DHL. We cannot guarantee the shipping company used to deliver your products. Your order may be shipped in multiple boxes from different carriers.

 

Process Time and Cut-off Time

Orders take 24hrs to process and transit times vary. Shipping cut-off for JDMuscle is 3:00pm EST. Freight shipping will require an appointment for pick-up which might take a few days extra.

 

Fees

International orders are subject to higher shipping fees then notified on the site and we reserve the right to add to it. Any modifications to an address after the order is placed may subject to a fee. The flat rate fee for a single smaller package is $20, and for larger or multiple packages the fee is not limited to $60. For International shipping please send us an email(sales@jdmuscleusa.com) with your full address and items to purchase.


 
Freight Shipping(Please read carefully)

Any orders shipped Via Truck Freight which requires you to be available at the time of receipt. There is a possibility the trucking company will try to schedule a delivery time with you. At the time of delivery, the driver will hand you the delivery receipt also referred to as the bill of lading, you will use this to notate any damages to the shipment. It is important that you fully inspect the shipment from all sides and notate any dents, punctures or rips in the outside packaging on the delivery receipt. Once you've inspected your shipment from the outside, you will need to open it and check the product in its entirety for damages and notate them if any. If there is no damage sign for the package and enjoy! In the rare case, you do find that your order arrived with damages, it is important you follow these steps. 

- Do not refuse the product 

- Document the damages in as much detail as possible on the Bill of Lading 

- Take numerous photos from all angles (including packaging) 

- Keep the product and contact the shipping company to start the damage claim 

- Contact us either by phone or email for the next steps In the situation where the delivery driver is unable to wait for you to open and inspect your product, simply document "driver was unable to wait for inspection." 

All damage must be noted on the Bill of Lading before signing and initiating a damage claim. If the damage is not notated before signing for the item it is assumed to be in good condition. This will forfeit the ability for a shipping claim and you will not be eligible for refund or replacement.

 

Returns

Our policy lasts 30 days. If 30 days have gone by since your purchase, unfortunately we can’t offer you a refund or exchange. Please send an email to sales@jdmuscleusa.com to set up a return.Please do not send your purchase back to the manufacturer.
 
 To be eligible for a return, your item must be unused and in the same condition that you received it. It must also be in the original packaging.
   

Additional non-returnable items:

  • Gift Cards
  • Special-ordered / custom item
  • Wheels

There are certain situations where only partial refunds are granted (if applicable) 

  • Any item not in its original condition, is damaged or missing parts for reasons not due to our error
  • Any item that is returned more than 30 days after delivery

 

Cancellation

You have 7 days to cancel an order, once the order has been packaged/ tracking number has been created, a cancellation is not allowed.

Full refund will be issued if the order has not been shipped, otherwise buyer will be responsible for a 10% restock fee and return shipping.

Special-ordered item cannot be canceled.


Refunds (if applicable)
 Once your return is received and inspected, we will send you an email to notify you that we have received your returned item. We will also notify you of the approval or rejection of your refund.
 If you are approved, then your refund will be processed, and a credit will automatically be applied to your credit card or original method of payment, within 7 days. Some brands/products might be subject to a restocking fee up to 25%, please check with us prior before purchase.
 
Late or missing refunds (if applicable)
 If you haven’t received a refund yet, first check your bank account again. Then contact your credit card company, it may take some time before your refund is officially posted.Next contact your bank. There is often some processing time before a refund is posted and can take up to 10 business days in rare cases
 If you’ve done all of this and you still have not received your refund yet, please contact us at sales@JDMuscleUSA.com.
  

Sale items (if applicable)
 Only regular priced items may be refunded, unfortunately sale items cannot be refunded.
 
Exchanges (if applicable)

We only replace items if they are defective or damaged. If you need to exchange it for the same item, send us an email at sales@JDMuscleUSA.com
 
Gifts
 If the item was marked as a gift when purchased and shipped directly to you, you’ll receive a gift credit for the value of your return. Once the returned item is received, a gift certificate will be mailed to you.If the item wasn’t marked as a gift when purchased, or the gift giver had the order shipped to themselves to give to you later, we will send a refund to the gift giver and he will find out about your return.
 
Shipping

You will be responsible for paying for your own shipping costs for returning your item. Shipping costs are non-refundable. If you receive a refund, the cost of return shipping will be deducted from your refund. Depending on where you live, the time it may take for your exchanged product to reach you, may vary. If you are shipping an item over $75, you should consider using a trackable shipping service or purchasing shipping insurance. We don’t guarantee that we will receive your returned item.

 

 

 

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GrimmSpeed Post MAF Hose Ki - Black Subaru WRX/STi 2018-2020

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