Not legal 1 class
Two-stroke exhaust must remain stock. Stinger insert only. · RAS.4.5
IJSBA · Exhaust
Aftermarket expansion chamber / tuned pipe (2-stroke)
The highest-value 2-stroke performance part and the one with the sharpest class split.
If a customer races Ski Lites or Runabout Stock, a pipe is a trailer-queen purchase. Say so on the product page.
Where it stands, class by class
12 classes, grouped by the answer rather than listed one by one, because an answer that holds for a class usually holds for every class that borrows its rules.
Not legal 1 class
Exhaust must remain stock as supplied by the manufacturer. Only a stinger insert and cooling lines are allowed. · SKL.3.6
Legal, within limits 1 class
Manifold, head pipe and expansion chamber allowed, but exhaust may NOT be relocated and the exit opening may not exceed 2 inches. · VSKL.3.7
Legal, within limits 1 class
Two-stroke manifold, head pipe, expansion chamber and the chamber-to-waterbox hose may be aftermarket. Exit location and opening size must not change.
Legal, within limits 1 class
Kawasaki, Yamaha and Polaris may relocate and replace the chamber. Sea-Doo HX must retain the unmodified stock HX exhaust. Wet-style only; dry pipes and water-jacketed chambers prohibited.
- Sport Spec · none - this document uses ALL-CAPS section headings, not numbered rules
Legal, within limits 1 class
Two-stroke chamber allowed; exit may not be relocated, OEM waterbox may not be modified, exit opening may not be oversized. · RAL.4.7
Legal 1 class
VSC.3.7
- Vintage SC · VSC
Legal 1 class
VX2.3.7
- Vintage X2 · VX2
Legal 1 class
VSK.3.7
- Vintage Ski · VSK
Legal 1 class
FREST.3.7
- Freestyle · FREST
Legal 1 class
Manifold, head pipe, expansion chamber, waterbox and muffler modified or aftermarket. · SKGP.3.7
Legal 1 class
SPGP.5.9
- Sport GP · SPGP
Aftermarket expansion chamber / tuned pipe (2-stroke): if the rule your class applies reads differently to you, or the rulebook has changed since this was read, ask. We answer with the section we read it from, or that we have not read it. Ask a rules question.
Every IJSBA class · where the rulebooks differ · signed checks on parts the shop sells.
Exhaust · two stroke · legal outright in 10 of 12