IHRA · Exhaust
IHRA answers this part for 29 of its classes. 3 of those answers are permissions, with or without limits attached, and 26 are not. 26 are inferred from how the class is written rather than quoted from a rule naming this part.
29 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 permitted, not listed in the rules Our reading, not a rule we can quote at you. This class requires the craft to stay stock except where the rules allow otherwise, and this part is not on the list.
No rule, this is an open class Our reading, not a rule we can quote at you. This class carries no stock clause at all, so anything unlisted appears to be open. The rulebook does not say so in terms.
Not permitted, not listed in the rules 22 classes
On a closed list an unlisted modification is not permitted. · A.2.2, J.1
Legal, within limits 1 class
Waterbox must be retained; aftermarket permitted with a through-hull exhaust pipe. STRAIGHT PIPES NOT PERMITTED. · DD.1
Legal, within limits 1 class
Must be retained; aftermarket with through-hull pipe. No straight pipes. · DD.2
Legal, within limits 1 class
Repairable only if the original internal configuration is unchanged. · M.4.3
No rule, this is an open class 3 classes
The class states only what it bans and calls itself run what you brung, against a section DD preamble that says anything unlisted is illegal.
No rule, this is an open class 1 class
No restriction in section CC, and CC.1 permits any modification it does not restrict.
Aftermarket or modified waterbox: 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 · signed checks on parts the shop sells.
Exhaust · two and four stroke · legal outright in 3 of 29