IJSBA Ruling Update: RIVA Intake Manifold Upgrade Kit for Yamaha Four Stroke The IJSBA has received an excessive amount of inquiries about the Stock Class legality of the Riva Intake Manifold Upgrade Kit. This part is advertised as a manifold upgrade kit. IJSBA Rule 6.6.1 anticipates modifications to be between the flame arrestor and throttle body when there is no airflow sensor. However, when there is an airflow sensor, the ducting leading up to the airflow sensor may be modified. The IJSBA has previously allowed mesh, located in the manifold, that served as part of the backfire protection system to be removed so long as the required backfire standards (as dictated in 6.6.1) are met. However, it was ruled that the manifold could not be modified outside of removing the backfire prevention device. The Riva Manifold Upgrade kit replaces a wire mesh insert with a an insert that does not contain the mesh.  This matter was submitted to the technical committee to resolve any conflict in provisions. After lengthy discussion and consultation, the IJSBA is ruling that allowing this part in Stock Class is consistent with prior rulings and is the type of modification that is anticipated by 6.6.1. This ruling is largely grounded in the fact that this modification is upstream of the airflow sensor and that the insert maintains the same dimensions as the original passage (less the mesh filter). Therefore, the insert only does what is necessary to relocate the backfire protection from the manifold to the air filter section while creating no additional size in the manifold air passage. The IJSBA strongly cautions the PWC community, especially product developers, that this ruling applies only to this particular part and application. The IJSBA shall maintain the theory and application of changing the flame arrestor/air intake ducting as permissible and compatible with Stock Class. However, any modifications outside of the ducting and filters will be met with the strictest scrutiny.  For questions about this ruling, or any other tech questions, please email tech@ijsba.com or call +1-(714)-751-8695. The APBA will also following the ruling on this part as made by the IJSBA.