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Class Legality

IHRA · Exhaust

Aftermarket head pipe and exhaust manifold, 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. 10 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

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.

OEM part required 1 class

W.1 keeps the craft OEM stock and W.2.6 lists no aftermarket manifold or head pipe. The manifold may be drilled and tapped for air fuel ratio and exhaust gas temperature sensor mounts, the OEM resonator between the water box and the outlet may be removed, the water box stays in its OEM configuration, and the external outlet may be relocated or aftermarket. · W.1, W.2.6

OEM part required 1 class

Z.3.3 keeps a two-stroke exhaust system stock, with only a stinger insert to reduce its inside diameter, and Z.2.5 lists no aftermarket manifold or head pipe for a four-stroke, allowing a manifold previously drilled or tapped once the holes are filled or capped, and flange removal. · J.1, Z.2.5, Z.3.3

OEM part required 1 class

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

Not permitted, not listed in the rules 1 class

AA.2.6 lists no aftermarket manifold or head pipe and allows only removal of the exhaust restrictor plate, with the original outlet diameter unaltered. · A.2.2, J.1, AA.2.6

Not permitted, not listed in the rules 1 class

N.2.5 lists no aftermarket manifold or head pipe: aftermarket piping may route exhaust only from the water box to the outlet pipe, the water box and manifold outlet may not be modified, and holes previously drilled or tapped in the manifold must be filled or capped. · A.2.2, J.1, N.2.5

Not permitted, not listed in the rules 1 class

Y.2.5 lists no aftermarket manifold or head pipe: a manifold previously drilled or tapped may be used with the holes filled or capped, flanges may be removed, and air fuel ratio and exhaust gas temperature sensor mounts may be drilled and tapped into it. The OEM resonator may be removed, the water box stays OEM, and the external outlet may be relocated or aftermarket. · A.2.2, J.1, Y.2.5

Not permitted, not listed in the rules 1 class

L.2.5 lists no aftermarket manifold or head pipe: the OEM exhaust manifold may be drilled or tapped if the holes are sealed, aftermarket hose or piping is allowed only from the water box to the exhaust outlet, and the water box and manifold outlet may not be modified. · A.2.2, J.1, L.2.5

Not permitted, not listed in the rules 1 class

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

Not permitted, not listed in the rules 1 class

R.2.5 lists no aftermarket manifold or head pipe and allows only the use of an OEM manifold previously drilled or tapped, with the holes properly sealed. · A.2.2, J.1, R.2.5

Not permitted, not listed in the rules 1 class

Q.2.5 lists no aftermarket manifold or head pipe and allows only the use of an OEM manifold previously drilled or tapped, with the holes properly sealed. · A.2.2, J.1, Q.2.5

Legal, with conditions 1 class

Model-dependent. On the Kawasaki X2 pre-2005, the X2 2005 to 2007 and the Yamaha WaveBlaster 701, WET-STYLE SYSTEMS ONLY, with dry-type systems and water-jacketed chambers prohibited and no tuned portion outside the hull. Electronic water injection is prohibited on all models. On the Sea-Doo HX the stock exhaust and water box must be unmodified, with no spray bars, stinger sprayers or water injectors, factory water routing and no bypass systems, and larger bolts or studs allowed. · U.2.3

Legal, with conditions 1 class

Model-dependent. M.6.1.4 opens an aftermarket wet pipe exhaust system on the Kawasaki SXR800, which reaches its head pipe and manifold. Whether a 701 SuperJet's wet pipe under M.6.2.1.2 may bring its own head pipe is not stated, and every other two-stroke keeps the stock pipe with only a stinger reducer and water fitting (M.4.1), while a four-stroke SuperJet may change only the hose from water box to outlet (M.4.2). · M.4.1, M.4.2, M.6.1.4, M.6.2.1.2

Legal, with conditions 1 class

Model-dependent. A four-stroke entry keeps its manifold outlet unmodified and may only run aftermarket piping from the water box to the outlet pipe, as Four Stroke Ski Lites allows (P.1, N.2.5). On a two-stroke entry P.2.1 frees the manifold, head pipe, expansion chamber, gaskets and the hose to the OEM water box, with the exhaust exit kept in place and at its original opening size. · P.1, N.2.5, P.2.1

Legal, with conditions 1 class

Model-dependent. On four-stroke entries removal of the plastic resonator is permitted (BB.2.6). On two-stroke entries the manifold, head pipe, expansion chamber, gaskets and the hose to the OEM water box may be aftermarket, the exhaust gas location may not be relocated, the original opening size must be kept, THE ORIGINAL WATER BOX IS REQUIRED AND UNMODIFIED, and no tuned portion may sit outside the hull. · BB.3.4

Legal, with conditions 1 class

Exit may relocate below the transom bond flange. No tuned components may protrude outside the hull. · T.2.5

Legal, with conditions 1 class

Manifold, head pipe, water box, expansion chamber, muffler. Exit may relocate to the transom but must not extend beyond the hull. · S.2.5

Legal, with conditions 1 class

No tuned portion may extend outside the hull. · CC.2.2

Legal, with conditions 1 class

Four-stroke (V.4.4): no tuned portion may protrude beyond the hull; exit may relocate to the transom below the bond flange. · V.2.5

Legal, with conditions 1 class

Valve count must remain unchanged. Tuned portion must not extend beyond the hull. Exit may move to the transom below the bond flange. · X.2.5

Legal, with conditions 1 class

DD.7 allows a turbo and regulates its header in its own words ("Watercooled Only, No Hot Headers"), and a turbo cannot run without a manifold to feed it, so this cell reads DD.7 as presupposing a watercooled header or exhaust manifold for the turbo and the pipe returning its exhaust to the existing water box. That is a reading of what DD.7 presupposes, not a listed permission, and a dry or uncooled header stays banned. · DD.7

Legal 1 class

Exit may be relocated to the transom. · K.2.5

Aftermarket head pipe and exhaust manifold: 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 IHRA class · where the rulebooks differ · checks on parts the shop sells · how this site reads a rulebook.

Exhaust · two and four stroke · legal in 12 of 29 answered, 10 with conditions

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BaddJet Class Legality