Relocated or aftermarket through-hull outlet, IHRA

IHRA answers this part for 29 of its classes. 2 of those answers permit the part outright and 10 permit it with stated conditions, leaving 17 that do not. 3 of the ones that do not are classes we read as open rather than as refusing it. 14 are inferred from how the class is written rather than quoted from a rule naming this part.

This page is IHRA only, and the bodies do not agree. The same part under IJSBA. Which one applies to you is decided by whoever sanctions the race you enter.

Where it stands, class by class

29 classes, grouped where the same rule gives the same answer rather than listed one by one, because an answer that holds for a class usually holds for every class that borrows its rules.

What each answer below means

Not legal: This comes off. The rules refuse it in this class.
OEM part required: This comes off. Only the part the manufacturer fitted is allowed here.
Not permitted, not listed in the rules: Treat it as coming off. The class requires the craft to stay stock except where the rules allow otherwise, and this part is not on the list, so this is our reading rather than a rule we can quote at you.
Legal, with conditions: Keep it, but measure it: the rules permit this part only inside stated limits.
Legal: Keep it. The rules permit this part in this class.
No rule, this is an open class: Probably keep it. The class carries no stock clause at all, so anything unlisted appears to be open. The rulebook does not say so in terms, and this is our reading rather than a permission anybody wrote down.

Not legal 1 class

A two-stroke entry may not relocate the exhaust gas exit and must keep its original opening size under P.2.1. A four-stroke entry inherits N.2.5 through P.1, which frees only the piping between the water box and the outlet pipe and never lists the outlet, so a change there is not permitted under the closed list. · P.1, N.2.5, P.2.1, J.1

Ski Limited

Not legal 1 class

BB.3.4 states that the exhaust gas location cannot be relocated and the original size opening for the exhaust exit must be maintained; only the through-hull outlet flap and the plastic resonator may be removed. · BB.3.4

Runabout Limited

OEM part required 1 class

Must remain OEM. Stinger-diameter reducing insert allowed; cooling lines may be added to the insert. · O.2.5

Ski Lites

Not permitted, not listed in the rules 8 classes

On a closed list an unlisted modification is not permitted. · A.2.2, J.1

Not permitted, not listed in the rules 1 class

N.2.5 allows aftermarket piping from the water box to the exhaust outlet pipe and bars changes to the water box and manifold outlet; the outlet itself is not listed, and under J.1 and A.2.2 an unlisted modification is not permitted. · N.2.5

Four-Stroke Ski Lites

Not permitted, not listed in the rules 1 class

Z.2.5 allows previously drilled manifolds if sealed and the removal of exhaust flanges on four-strokes; Z.3.3 keeps the two-stroke exhaust stock with a stinger insert; neither names the outlet, and under J.1 and A.2.2 an unlisted modification is not permitted. · Z.2.5, Z.3.3

Runabout GP3

Not permitted, not listed in the rules 1 class

The class exhaust rule opens only the hose between the waterbox and the outlet on four-strokes (M.4.2) and a stinger reducer and water fitting on two-strokes (M.4.1); the outlet itself is not listed, and under J.1 and A.2.2 a modification not listed is not permitted. · M.4.2

Ski GP3