Spark 2-Up Rear Exhaust Kit — Install Guide

GT40 Marine | SKU GT40-SD-EXH-SPARK2 | Stainless Rear Exhaust + Resonator Delete | Rev 1.0 — 2026-05-24

Fitment

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

Not for: Spark 3-Up — the 3-Up hull has different exhaust routing geometry, separate kit needed. Not for any 1503 4-TEC or 1630 ACE platform. Confirm hull is the 2-Up configuration (shorter hull, two-seat capacity) before install — the 3-Up vs 2-Up is the most common installation mistake on the Spark platform.

In the Box

(1) GT40 Spark 2-Up stainless rear exhaust outlet, hand-formed
(1) Resonator delete tube, billet aluminum, anodized black
(1) Stainless steel exhaust gasket, fire-rated, marine-grade
(3 ft) High-temperature silicone water hose, 3/4" ID
(2) Stainless worm-gear hose clamps, #12
(4) M8 × 25 mm SHCS — manifold mounting (high tensile, marine-grade)
(4) M8 stainless flat washers
(1) High-temperature exhaust sealant tube, 4 oz
(1) Hardware bag — spare gasket, spare clamps
(1) GT40 product registration card
(1) This guide

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

Tools Required

10 mm / 13 mm sockets + ratchet, 3/8" drive
T20 + T25 Torx drivers
5 mm + 6 mm hex (Allen) keys
1/4" drive torque wrench, 5–30 Nm range
Hose-clamp pliers
Marine-grade exhaust sealant applicator (small brush)
Flashlight or headlamp
Shop towels
Marine-grade copper anti-seize compound

Safety

Read in full before starting.

Battery disconnected for the duration of the install.
Cold engine only. Spark exhaust retains heat for over an hour after operation.
Eye protection mandatory when working around the exhaust manifold.
Hand protection. Sharp flange edges on marine exhaust.
No smoking / open flame.
The Spark is a smaller hull — the engine bay access is tight. Plan extra time for fastener access.

If you are not comfortable with PWC exhaust system work, take the install to a certified marine technician.

Pre-Install Checklist

[ ] Watercraft on stable trailer or stand
[ ] Hull HIN confirmed as 2-Up (NOT 3-Up)
[ ] Battery negative disconnected and isolated
[ ] Engine bay clean and dry
[ ] Factory resonator + rear-outlet routing photographed
[ ] Marine-grade anti-seize ready
[ ] 90 minutes minimum for install + 2 hours sealant cure scheduled before first start

Step-by-Step Install

Step 1 — Access the Engine Bay

Remove the seat. The Spark engine bay is more compact than larger Sea-Doo platforms — the seat removal alone reveals adequate access.

Disconnect the battery negative terminal.

Step 2 — Identify the Factory Resonator and Rear Exhaust

The Spark 2-Up exhaust system consists of:

A short factory resonator (cylindrical chamber, ~6 inches long)
A short rear-outlet pipe connecting the resonator to the through-hull discharge

Note: the Spark uses a smaller-diameter exhaust than the 1503/1630 ACE platforms — the M8 hardware reflects the lighter exhaust mass.

Step 3 — Remove the Factory Resonator and Rear Exhaust

Disconnect any cooling water injection lines feeding the resonator (1 small hose connection, spring clamp)
Loosen the resonator-to-manifold band clamp (10 mm)
Loosen the resonator-to-rear-outlet band clamp (10 mm)
Lift the resonator and rear-outlet assembly out as a single unit — ~3 lbs total
Inspect the manifold outlet flange — must be flat, no carbon scoring

Set the stock components aside. Do not discard if you may sell the craft in stock form later.

Step 4 — Install the GT40 Resonator Delete Tube

Apply marine anti-seize to all 4 M8 × 25 mm SHCS threads
Position the supplied stainless gasket on the manifold flange
Apply a thin even bead of high-temperature exhaust sealant around the gasket's outboard face
Position the GT40 resonator delete tube against the gasket
Thread the 4 M8 SHCS through the tube flange with flat washers — hand-tight only
Confirm the tube is square to the manifold (no rotational offset)
Torque the 4 bolts to 22 Nm (16 ft-lb) in a star pattern across two passes — first pass at 12 Nm, second pass at 22 Nm
Wipe any sealant squeeze-out

Step 5 — Install the Stainless Rear Exhaust Outlet

Apply marine anti-seize to the stainless outlet's mounting flange threads
Position the outlet against the resonator delete tube's exit flange
Thread the supplied V-band clamp around both flange edges
Snug the clamp finger-tight
Rotate the outlet to align with the through-hull exit point — outlet must enter the through-hull fitting straight
Once aligned, torque the V-band clamp to 18 Nm (13 ft-lb) in two passes
Verify the outlet exits the hull cleanly — no contact with hull fiberglass

Step 6 — Reconnect Cooling Water Injection

The resonator delete preserves the original cooling water reintroduction at the top of the delete tube (the design includes the same injection port location).

Cut the supplied silicone water hose to length
Slide #12 clamps onto each hose end
Push the hose onto the engine block water source fitting, then the delete tube's water injection port
Tighten both clamps to 3 Nm (27 in-lb) equivalent
Verify hose routing avoids contact with the hot delete tube — minimum 20 mm clearance

Step 7 — Allow Sealant Cure Time

Exhaust sealant requires a minimum of 2 hours cure time before engine start. Do not skip.

Step 8 — Reassembly and First Start

After cure:

Walk the engine bay — every fastener, every clamp, every hose joint
Confirm no tools or hardware remaining
Reconnect the battery negative terminal — torque to 10 Nm (89 in-lb)
Replace the seat
Connect the engine cooling flush hose
Start the engine on the trailer
Idle for 60 seconds — listen for any exhaust leak
Verify cooling water flow through the new injection point — observe steam from the rear exhaust outlet
Bring the engine to 3000 RPM briefly — confirm new exhaust note (significantly louder than the muted factory Spark sound)
Scan with the appropriate Spark diagnostic tool — no new fault codes
After shutdown, visually inspect the resonator delete tube for any sealant migration

If clean: install complete.

Post-Install

Break-In

First water test should run a conservative throttle profile for the first 5 minutes. The Spark engine is smaller and less forgiving of thermal shock than the larger platforms — be conservative on the first run.

The exhaust note will be substantially louder than stock. The Spark's factory resonator significantly attenuated the engine sound; removing it exposes the raw 900 ACE character. Expect a more aggressive note especially at 4000+ RPM.

Tuning

The Spark 900 ACE responds modestly to exhaust changes. Expect 2-4 HP gain on a stock craft, more if paired with a Spark-specific tune. The Spark's narrower performance envelope means exhaust gains are smaller than on the 1503 / 1630 platforms.

Service

Inspect the resonator delete tube every 25 run hours for any sealant weep
Re-torque the 4 M8 SHCS at the first 10-hour service to 22 Nm
Inspect the stainless outlet annually
Inspect the cooling water injection hose every 25 hours — replace if any cracking
After 100 hours, plan a full exhaust sealant inspection (Spark engine bays accumulate more salt residue per hour than larger platforms because of the smaller air gap)

Troubleshooting

| Symptom | Likely Cause | Fix |

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

| Sharp ticking at manifold-to-tube joint | Gasket failure | Drain, replace gasket + sealant, reinstall |

| Stainless outlet doesn't seat in through-hull | Possible 3-Up hull error | Verify hull is 2-Up, contact support if 3-Up |

| Exhaust gas smell in engine bay | Resonator delete tube leak | Retorque to 22 Nm, monitor, re-seal if persists |

| Steam in the engine bay after run | Cooling water injection hose failure | Inspect, replace hose, retorque clamps |

| Engine performance unchanged | Spark exhaust gain is modest | Spark gains 2-4 HP from exhaust — pair with tune for more |

| Excessive engine bay heat | Insufficient hose clearance | Verify 20 mm minimum clearance, reroute hose |

If symptoms persist after the checks above, contact GT40 Marine support before further operation.

Torque Reference Summary

| Fastener | Torque |

|---|---|

| Resonator delete tube to manifold M8 SHCS (all 4) | 22 Nm / 16 ft-lb |

| Stainless outlet V-band clamp | 18 Nm / 13 ft-lb |

| Cooling water injection #12 hose clamps | 3 Nm / 27 in-lb (snug, no hose-wall cut) |

| 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.

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 installation
Damage from premature engine start before full sealant cure
Damage from operation without proper cooling water flow through the new injection point
Damage from incorrect hull-type installation (3-Up vs 2-Up)
Damage to stainless components from galvanic corrosion in saltwater 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, and a description of the failure mode. Response within two business days.

Support

Email: support@gt40marine.com
Site: gt40marine.com
Install help: include the GT40 SKU above and your hull serial number in any support correspondence

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