2015-2017 GT & GT350

Whipple Stage 4

Inlet Path Sound Tube Installation Guide SKU 505, 900 & 905

This kit offers higher levels of rotor sound (whine) within the cabin due to the direct path from the inlet through the firewall and the larger ID.

This Kit requires that the firewall is drilled.


  1. 1 x drill bit
  2. 1′′ straight hose barb
  3. 1 x diaphragm cap
  4. 1 x Blade
  5. Sound Tube
  6. 2 x rubber grommets one wide groove one narrow
  7. 1 x Zip tie

Fold the carpet down in the driver side footwell behind the brake pedal to the left of the steering column & secure by inserting a small screw as shown in the image through the carpet.

Pull the retaining clip off the carpet stud to enable the cutting of the insulation.

Cut the insulation along the horizontal line with supplied blade.

Use a center punch to mark the drilling point for the hole. Draw a line across from the steering column bracket point. Draw a second vertical line approximately ¼” from the raised sheet metal contour as shown the image.

To determine the exact point, you will be able to feel (using your fingers) After using the center punch to mark the drill entry point, drill a pilot hole first then using the supplied drill bit at low speed and using windex as lubrication and cooling to avoid (overheating) and damage to the drill bit. Drill on low speed and keep pumping the windex flooding the bit.

Make sure the drill and hole saw is flush with the fire wall sheet metal as not to catch and edge and damage drill bit. Drill all the way through with the bit.

Use protective cloth or paper towel taped to the firewall to catch the drill debris and filings produced during the drilling process. Vacuum filings after drilling.

Hole drilled through firewall. A black felt insulation on the engine side will need to be cut out with supplied razor.

With supplied step drill bit drill the inside curve of the inlet elbow in the middle from end to end. Use the casting seam in the plastic elbow and measure up ¾” and mark for drilling the hole. Clean the edges with a razor or sand lightly (don’t remove too much material with razor). install the narrow grooved grommet into the hole, making sure it’s completely seated grease will help seat the grommet completely.

Mark and drill 3/4” from the plastic seam edge and in the middle of the 2 ends.

After rubber Grommet is installed push the 1” hose barb into the grommet from the inside with supplied grease to help seat and seal.

Before the inlet elbow is installed push the sound tubes smaller end over the hose barb while holding the hose barb fitting from inside. Fully seat the sound tube so it’s completely compressed against the housing and grommet. Make sure the hose barb fitting on the inside doesn’t push in while installing. The hose barb flange on the inside should be compressed tight against the grommet. Supplied grease will help in seating the sound tube to the hose barb.

This step needs to be done before the curved plastic elbow is installed

Install the supplied wider grooved grommet working into the hole which was cut in the firewall. Use supplied grease on the bare metal edges for protection. Add some grease to the grooves of the grommet to prevent corrosion.

Install the sound tube through the firewall hole with wider grooved grommet in place. It should be possible to fit your entire arm into the space and your hand all the way to the firewall.

Use supplied grease inside the grommet and on the tube end which will aid in pushing the sound tube hose end through the grommet in the firewall.

Watch video

The rubber diaphragm must be used to seal off the sound tube from the inlet path. This ensures the MAF and calibration is not changed. Use supplied grease on the hose end and push the cap on the end of the sound tube fully seating the cap. You will need helper to hold the engine side of the sound tube to ensure it’s compressed together.

Warning: failure to install the diaphragm cap properly could result in unmetered air and poor running condition.

This illustrates how the cap would install to the sound tube. Warning: failure to install the diaphragm cap properly could result in unmetered air and a lean condition.

Fold back the carpet insulation into its original position
and use the supplied blade to trim the edge of the carpet to the diameter of the sound tube. Sound tube completely installed with OEM fit and finish.

We appreciate your business and hope you enjoy the increased rotor whine!

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