Is the value change of CACHE_SIZE parameter on internal sequences (owned by SYS) supported?

Hello.

Can anyone answer this question? There are several sequences on which we have seen large contention (e.g. enq: SQ contention or row cache lock on dc_sequence)

SYS.ST_OPR_ID_SEQ, SYS.MVREF$_STATS_SEQ, SYS.PARTITION_NAME$, SYS.SCHEDULER$_INSTANCE_S, SYS.LINK_SOURCE_ID_SEQ.

Can we increase the cache size in these sequences without worrying about the implications for database supportability (since they are SYS schema objects)? All sequences have default size of cache set (20) except link_source_id_seq whose value is only 10. It is the 8-node RAC database - we think the cache size on these sequences should be much larger.