ok i just got my b20vtec running which has been rebuilt with 11.5 compression arias pistons. but it sounds like its knocking. ive done a search and have found out that arias pistons are know for being noisy. is this true cause at idle the knock/slap isnt too bad. just sounds like a diesel. is this common?

 

yes it is common.
Low silicon pistons expand alot more than others, they are very strong.