rod bolts
but the ls1s are proven sub 7000 rpm with the factory bolts.
you said you set the limiter to 6400,with the dose of nitrous
ye may run max limited revs initially 1st-2nd gear then limit the rpms to a more feasable 6200rpm with the gas because the readjusted to a more retarded ignition timing required to ensure detonation is minimised(remmembering detonation is the no1 cause of rod bolt failures not the rpms by itself) so ensure proper fuel control by compensating on ye map by retarting a few degrees which interm will result in max power lower rpms.which it goes hand to hand with the higher load demands and your compromised for nitrous tune with the new found optimum for max high load rpms.
beats putting in new rod bolts if its all ok.



