Rear Exhaust Outlet + Custom Tip — Install Guide

GT40 Marine | SKU GT40-SD-EXH-OUTLET | Through-Hull Rear Exhaust Outlet Kit | Rev 1.0 — 2026-05-24

Before You Start — Decision Tree

This kit installs a through-hull rear exhaust outlet — the visible discharge fitting at the rear of the hull. Two hull-specific geometry branches apply:

| # | Question | Branch |

|---|---|---|

| 1 | Is this an RXT/GTX (S3 hull)? | Branch A — RXT/GTX S3 |

| 2 | Is this an RXP-X (T3 hull)? | Branch B — RXP-X T3 |

| 3 | Is this a 2024+ RXP-X 325? | Use Branch B — T3 but note 2024+ shim notes |

| 4 | Is this a Spark? | Do NOT use this kit — Spark uses a different outlet geometry |

| 5 | Do you have a 2-3/4" hole saw? | Required tool — confirm before starting |

Hard prerequisite: this kit assumes the customer has already removed the factory through-hull outlet OR the hull never had one (some performance builds). If the factory outlet is in place, removal is the first step.

Fitment

| Platform | Models | Year | Hull Type |

|---|---|---|---|

| Sea-Doo | RXT-X 300 | 2018–present | S3 |

| Sea-Doo | RXT-X 325 | 2024–present | S3 |

| Sea-Doo | GTX 300 / Limited 300 | 2018–present | S3 |

| Sea-Doo | GTX Limited 325 | 2025–present | S3 |

| Sea-Doo | Wake Pro 230 | 2018–present | S3 |

| Sea-Doo | RXP-X 300 | 2016–present | T3 |

| Sea-Doo | RXP-X 325 | 2024–present | T3 (with shim) |

Not for: Spark (different outlet geometry, separate kit), 1503 4-TEC legacy hulls (use the kit-specific outlet bundled with the 215 exhaust). Confirm hull type (S3 vs T3) before install.

In the Box

• (1) GT40 stainless steel rear exhaust outlet, mirror-polished, 304-grade marine stainless
• (1) Custom exhaust tip, brushed finish (interchangeable with the polished outlet via the same V-band interface)
• (1) GT40 S3 hull adapter flange (for RXT/GTX) — included regardless of hull type
• (1) GT40 T3 hull adapter flange (for RXP-X) — included regardless of hull type
• (1) Transom template, paper, for S3 hulls (2-3/4" hole, specific X/Y placement)
• (1) Transom template, paper, for T3 hulls (2-3/4" hole, specific X/Y placement)
• (1) High-temperature marine sealant (NOT thread sealant — purpose-built marine through-hull sealant)
• (1) V-band clamp, stainless, 2-3/4" ID
• (6) M6 × 20 mm SHCS — adapter-flange-to-hull mounting
• (6) M6 stainless flat washers
• (6) M6 nylon-insert lock nuts
• (1) Marine-grade rubber gasket, between adapter flange and hull
• (1) 2024+ RXP-X 325 shim kit (1 mm aluminum shim ring) — use ONLY on 2024+ RXP-X 325
• (1) GT40 product registration card
• (1) This guide

Verify all components present before starting. Missing parts: support@gt40marine.com.

Tools Required

• 8 mm / 10 mm / 13 mm sockets + ratchet, 3/8" drive
• T20 + T25 Torx drivers
• 4 mm + 5 mm hex (Allen) keys
• 1/4" drive torque wrench, 5–15 Nm range
• 2-3/4" hole saw (required — not supplied because most installers already own one; if needed, contact GT40 support for the specific spec)
• Hole saw arbor + pilot drill bit
• Center punch
• Drill (corded preferred for the hole saw cut, 1/2" chuck)
• File (for deburring the hull cut edge)
• Marine sealant applicator gun
• Painter's tape (for masking the template position)
• Shop towels
• Eye protection + respirator (fiberglass dust is hazardous to lungs)

Safety

Read in full before starting.

1. Battery disconnected for the duration of the install.
2. Eye protection MANDATORY during the hole saw cut. Fiberglass shavings cause permanent eye damage.
3. Respirator MANDATORY during the hole saw cut. Fiberglass dust is a chronic respiratory hazard — do not skip the mask.
4. Hand protection when handling cut hull edges. Raw fiberglass cuts are sharp and contaminated.
5. Work outdoors or in a well-ventilated space. Fiberglass dust must not be inhaled.
6. Confirm hull-cut location with the transom template BEFORE cutting. A misplaced hole CANNOT BE UNCUT. Mark thrice, cut once.
7. Do NOT use generic gasket sealer or RTV in place of the supplied marine sealant. Marine through-hull sealant has specific cure properties for saltwater exposure — substitutes will fail.
8. Do NOT over-tighten the adapter-flange bolts. Over-tightening causes hull material distortion and creates leak paths. Torque to spec — no exceptions.

If you are not comfortable with cutting a through-hull hole in your watercraft, take the install to a certified marine technician. This is the only step in any GT40 kit that involves permanent hull modification — a mistake here is permanent.

Pre-Install Checklist

• [ ] Watercraft on stable trailer or stand, drain plugs out
• [ ] Battery negative disconnected and isolated
• [ ] Hull type identified (S3 or T3) and matching template selected
• [ ] Existing through-hull outlet (if present) removed
• [ ] Hole saw assembled to arbor with pilot bit centered
• [ ] Painter's tape ready for template positioning
• [ ] Marine sealant at room temperature (proper viscosity)
• [ ] 60 minutes minimum for install + 24 hours sealant cure before first water test

Step-by-Step Install

Step 1 — Identify and Mark the Hull Cut Location

This is the most critical step in the install. Take your time.

1. Locate the rear transom of the hull
2. Select the correct template (S3 or T3) — verify by hull-type identification (RXT/GTX = S3, RXP-X = T3)
3. Position the template on the transom — the template has alignment notches that reference the bottom edge of the hull AND the centerline of the transom
4. Tape the template in place with painter's tape — do not let it shift
5. Using the center punch, mark the center of the 2-3/4" hole through the template
6. Remove the template and verify the punch mark is in the correct location by re-applying the template — should align perfectly

If the punch mark is incorrect, you have not cut anything yet. Re-do this step until correct.

Step 2 — Cut the Through-Hull Hole

Eye protection AND respirator MUST be worn for this step.

1. Apply the pilot drill to the center punch mark, drill a pilot hole completely through the hull wall (slow speed, light pressure)
2. Assemble the 2-3/4" hole saw to the pilot
3. Cut the hole at low speed (300-500 RPM), applying steady pressure
4. Do not force the saw — the hull material varies and forcing leads to chipped edges
5. Once the saw is through, remove the hole saw and the cut hull piece (the "core")
6. Discard the core — do not reuse
7. Inspect the cut edge — should be uniformly round, no chips, no major delamination
8. Deburr the cut edge with a fine file — light passes only, do not enlarge the hole
9. Vacuum all fiberglass dust from the area
10. Wipe the cut edge with a clean shop towel

Step 3 — Pre-Fit the Adapter Flange

Before applying any sealant, dry-fit the adapter flange to verify position:

1. Select the correct hull adapter flange (S3 or T3)
2. Position the adapter against the hull's exterior face, aligning the central hole
3. Mark the 6 mounting bolt locations through the adapter's mounting holes with a fine pencil
4. Remove the adapter
5. Drill 6 pilot holes at the marked locations (1/4" drill, through-hull)
6. Re-position the adapter and verify all 6 bolts will pass through cleanly

Step 4 — Apply Marine Sealant and Install Adapter Flange

1. Apply a continuous bead of the supplied marine sealant around the central hole's outboard edge (the side facing inward, where the adapter will seat)
2. Apply additional sealant around each of the 6 bolt holes
3. Position the supplied marine-grade rubber gasket onto the adapter's mounting face
4. Press the adapter flange against the hull, aligning the 6 bolt holes
5. Thread the 6 M6 × 20 mm SHCS through the adapter (from outside) into M6 lock nuts on the interior side of the hull (with flat washers under both head and nut)
6. Snug all 6 in a star pattern — DO NOT torque yet
7. Wait 5 minutes for sealant to begin its skin-cure
8. After 5 minutes, torque all 6 M6 SHCS to 8 Nm (71 in-lb) in a star pattern — over-tightening causes hull distortion, under-tightening allows leakage
9. Wipe any sealant squeeze-out with a clean rag

Step 5 — Apply 2024+ RXP-X 325 Shim (if applicable)

Skip this step unless installing on a 2024+ RXP-X 325 hull.

The 2024+ RXP-X 325 hull has a 1 mm thicker transom material than the 300HP variant. The shim ring compensates:

1. After the adapter flange is torqued, slide the 1 mm aluminum shim ring over the adapter's exit boss
2. The shim sits between the adapter's V-band groove and the outlet's V-band groove
3. This shim is invisible once the outlet is installed — internal use only

Step 6 — Install the Stainless Outlet or Custom Tip

Choose which finish to install — polished outlet OR brushed custom tip. They share the same V-band interface so the customer can swap finishes later.

1. Apply a thin smear of marine anti-seize on the V-band groove
2. Position the outlet (or tip) against the adapter flange's V-band interface
3. Slide the supplied V-band clamp around both flanges
4. Snug the clamp finger-tight
5. Rotate the outlet to the desired orientation (typically the outlet is rotated so any branding or design feature is upright)
6. Once aligned, torque the V-band clamp to 12 Nm (8.8 ft-lb) in two passes
7. Verify no rotation when pull-tested

Step 7 — Allow Sealant Cure Time

Marine sealant requires a minimum of 24 hours cure time before water exposure. Do not skip — the sealant must fully cure to maintain the hull seal under saltwater exposure cycles.

If you can wait 48 hours, recommended for saltwater operation.

Step 8 — First Water Test

After cure:

1. Walk the install area — every bolt, the V-band clamp, the sealant joint
2. Confirm no tools or debris remaining
3. Reconnect the battery negative terminal — torque to 10 Nm (89 in-lb)
4. Trailer the watercraft to a calm body of water
5. Launch on a quiet ramp
6. Inspect the through-hull adapter from inside the hull while floating — look for any water intrusion at the adapter-to-hull seal
7. If dry: idle for 60 seconds, monitor again
8. After 5 minutes of idle, brief throttle bursts (3000 RPM) — verify the outlet directs water properly aft, no spray into the hull
9. Return to dock, trailer out, inspect once more for any wetness around the adapter inside the hull

If clean: install complete.

Post-Install

Break-In

The marine sealant continues to cure under saltwater exposure for the first 100 hours of operation. During this period:

• Avoid extended saltwater dwells (overnight saltwater storage)
• Freshwater flush after every saltwater session
• Visually inspect the adapter-to-hull seal monthly

After 100 hours, sealant is fully cured and routine inspection (annual) is sufficient.

Polished vs Brushed Tip Swap

To swap between the polished outlet and the brushed custom tip:

1. Loosen the V-band clamp
2. Remove the current outlet/tip
3. Apply fresh marine anti-seize to the V-band groove on the new outlet/tip
4. Position, snug, torque the V-band clamp to 12 Nm
5. No sealant rework required — the adapter flange stays in place

Service

• Inspect the adapter-to-hull seal annually for any sealant migration or cracking
• Inspect the V-band clamp annually — re-torque to 12 Nm if any looseness detected
• Replace the V-band clamp every 5 years or 500 hours (saltwater operation degrades stainless faster than freshwater)
• Inspect the outlet for galvanic corrosion at the V-band interface annually

Troubleshooting

| Symptom | Likely Cause | Fix |

|---|---|---|

| Water intrusion at adapter-to-hull seal | Sealant not fully cured OR adapter under-torqued | Trailer immediately, dry the area, allow full 48-hour cure, retorque all 6 M6 to 8 Nm |

| Hull distortion visible around adapter | Adapter over-torqued | Carefully back off bolts 1/4 turn each, retorque to spec |

| Outlet rotates under load | V-band clamp under-torqued | Retorque V-band to 12 Nm |

| Outlet leaks at V-band interface | Anti-seize improperly applied OR V-band damaged | Disassemble, inspect both flange surfaces, replace V-band if damaged |

| Adapter flange visibly cracked | Catastrophic over-tightening — install error | Contact GT40 support — replacement adapter required |

| Galvanic corrosion at V-band | Saltwater exposure without sacrificial anode | Install marine anode kit, replace V-band clamp |

| Wrong hole position | Template misalignment during Step 1 | This cannot be undone — contact GT40 support for advice on professional hull repair + relocation |

If symptoms persist after the checks above, contact GT40 Marine support immediately. Hull-seal failures can cause sinking risk if ignored.

Torque Reference Summary

| Fastener | Torque |

|---|---|

| Adapter-flange-to-hull M6 SHCS (all 6) | 8 Nm / 71 in-lb |

| Outlet-to-adapter V-band clamp | 12 Nm / 8.8 ft-lb |

| Battery negative terminal | 10 Nm / 89 in-lb |

All torque values nominal — refer to current Sea-Doo factory service manual for any conflicting OEM specifications.

Critical note on torque: unlike most fasteners on a watercraft, the adapter-flange M6 bolts MUST NOT exceed 8 Nm. Over-torque causes hull distortion which creates leak paths. The spec is intentionally conservative.

Warranty

GT40 Marine warrants this kit free from defects in materials and workmanship for ninety (90) days from date of purchase. Warranty covers replacement of defective GT40-supplied components. Warranty does not cover:

• Damage from improper hull cut (template misalignment, hole saw error)
• Damage from premature water exposure before full sealant cure
• Damage from improper sealant (using non-marine sealants)
• Hull damage from over-torqued adapter fasteners
• Galvanic corrosion damage from saltwater operation without sacrificial anode protection
• Use on craft outside the listed fitment matrix

To submit a warranty claim: email support@gt40marine.com with order number, photographs of the installed kit (interior + exterior views of the adapter), hull HIN, and a description of the failure mode. Response within two business days. Hull-seal warranty claims are prioritized for response within 24 hours due to safety implications.

Support

• Email: support@gt40marine.com
• Site: gt40marine.com
• Install help: include the GT40 SKU above, hull HIN, hull type (S3 or T3), and photographs of the install in any support correspondence

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