iS / aS Suspension Power Filter — Install Addendum

GT40 Marine | Doc GT40-SD-INT-ISAS-ADDENDUM | Install Addendum to GT40-SD-INT-CF | Rev 1.0 — 2026-05-24

---

What This Addendum Covers

This addendum extends the standard Cold Air Intake Kit install procedure (GT40-SD-INT-CF) for craft equipped with the iS or aS rear suspension system. Read the main install guide first; this addendum overrides the standard procedure at the specific steps noted.

---

Fitment

Not for: Standard suspension craft (use the base GT40-SD-INT-CF guide without this addendum). Not for craft where the iS/aS suspension has been removed by a previous owner (in that case, verify the cooling and electrical systems are reverted to standard configuration before install).

---

Why iS / aS Is Different

The iS (intelligent Suspension) and aS (adaptive Suspension) systems use hydraulic actuators in the rear-deck area that:

• Cycle under power — the suspension travels actively during operation, which can pinch tools, hands, and hoses
• Have their own hydraulic lines in the engine bay, routed through the same area as the intake
• Use additional electrical relays mounted on the engine bay sidewall
• Add weight to the rear deck — when the deck is removed during install, it must be supported

This addendum walks through the suspension-specific safety and procedural changes.

---

Pre-Install Addendum — iS / aS Safety Lockout

Before any work in the engine bay, lock the suspension in service position. This prevents involuntary suspension travel during the install.

iS lockout procedure

1. Turn the key to ACC
2. Press and hold the suspension control buttons (left and right arrows simultaneously) for 5 seconds
3. The dash display will show "SERVICE MODE" — the suspension is now locked at full extension
4. Turn key to OFF — the suspension stays locked
5. Verify lockout — push downward on the rear deck firmly; the deck should not compress more than 5 mm

aS lockout procedure

1. Turn the key to ACC
2. Press the "ASC" button on the dash 3 times in rapid succession (within 2 seconds)
3. The dash display will show "ADAPTIVE OFF" — the suspension is now locked at the last-commanded position
4. Turn key to OFF
5. Verify lockout — push downward on the rear deck; movement should be physical compression only, no hydraulic response

If the suspension does NOT lock per the above procedures, do not proceed with the install. Take the craft to a certified BRP technician for suspension service first.

---

Modified Step Sequence (vs. base GT40-SD-INT-CF guide)

Step 1 — Access (MODIFIED)

After standard seat removal, the iS/aS engine bay access requires additional steps:

1. Remove the upper-rear inner panel (4 T25 Torx screws — these were added for iS/aS hulls and don't exist on standard hulls)
2. Inspect the iS/aS hydraulic line routing — note the line positions before any tool work
3. Mark any hydraulic line that crosses the intake install path with painter's tape — these lines MUST NOT be disturbed during install

Step 3 — Remove Stock Airbox (MODIFIED)

When lifting the stock airbox out, the iS/aS hulls have an additional clip on the airbox underside that secures one of the suspension hydraulic lines. This clip relocates to the GT40 adapter:

1. Before lifting the airbox out, identify the hydraulic line clip on the airbox underside
2. Carefully release the clip (it's a snap-fit, no fastener) — be gentle, the hydraulic line cannot tolerate side-load
3. Lift the airbox out
4. Retain the clip for installation on the GT40 adapter in Step 4

Step 4 — Install GT40 Intake Adapter (MODIFIED)

After the standard adapter mounting:

1. Install the retained hydraulic line clip on the GT40 adapter's pre-machined clip mounting boss (visible on the adapter's outboard face — small threaded boss with an M4 thread)
2. Snug the clip to 2 Nm (18 in-lb) with an M4 SHCS (supplied with the kit's hardware bag)
3. Re-route the hydraulic line through the clip — verify no twist, no kink

Step 5 — Coupler Install (NO CHANGE)

Follow base guide Step 5 as written. The coupler install is identical between standard and iS/aS hulls.

Step 7 — Filter Housing Install (MODIFIED)

The iS/aS hulls have approximately 5 mm less vertical clearance to the upper deck above the intake area than standard hulls. After installing the filter housing:

1. Verify clearance from the housing top to the upper deck — minimum 8 mm
2. If clearance is less than 8 mm: rotate the housing on its mounting clamp by 15 degrees outboard. This adjustment is acceptable on the iS/aS hulls because the airflow direction matters less than the absolute clearance

Step 8 — Reassembly (MODIFIED)

After standard reassembly:

1. Reinstall the upper-rear inner panel removed in modified Step 1 (4 T25 Torx screws, torque 2.5 Nm)
2. Verify all painter's tape markings from Pre-Install have been removed
3. Release the suspension lockout before water test:

• iS: turn key to ACC, hold suspension control buttons for 5 seconds, dash returns to normal mode
• aS: turn key to ACC, press ASC button 3 times rapidly, dash returns to normal mode

1. Cycle the suspension manually through its full travel range while the craft is on the trailer — confirm no tube/intake interference at extremes

---

Service Schedule Addendum

In addition to the base guide's service schedule:

• Every 25 hours: inspect the hydraulic line clip on the GT40 adapter — re-torque to 2 Nm if any looseness
• Every 50 hours: verify hydraulic line routing through the clip — no twist, no kink, no rub against adjacent components
• Annually: full iS/aS hydraulic system inspection per BRP service interval (this is a base BRP service, not GT40-specific, but should be on the radar of any iS/aS owner)

---

Troubleshooting Addendum

---

Connects to

• GT40-SD-INT-CF_COLD_AIR_INTAKE_KIT_INSTALL_GUIDE.md — base install guide this addendum extends
• GT40-SD-TUBE-260-BOV_INTERCOOLER_TUBING_INSTALL_GUIDE.md — also has iS/aS-specific notes for tubing install on the same suspension chassis

---

Support

• Email: support@gt40marine.com
• Site: gt40marine.com
• iS/aS-specific install help: include the GT40 kit SKU, hull HIN, model year, and confirmation of suspension type (iS or aS) in any support correspondence

Built in the United States. Designed for buyers who want the best.

---

This addendum is © 2026 GT40 Marine. All rights reserved.