Eh, they were displayed!! What do you think the safety car and course cars were??? Herrod modified XR6Ts. Not engine modified - but the suspension, brakes and wheels were Herrod.
As for gearboxes worries with the new turbo, go check performance forums and see what happens when you modify SXs, etc - dead diffs, gearboxes, clutches etc. This is exactly what some of the Jap car owners said about the XR6T - it's really no different to the situation they have.
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