2 clutch questions

1)So I installed dbo 650 in my xmr, and they told me not to instal the yellow black secondary cause the mud zillas dont need it, but there instructions say any 28 and bigger pure mud tire install the yellow black secondary, how do u guys think it would act like if I do, im looking for more bottom end,
2) THE CLUNK! its annoying and im wondering if I can put on a STM secondary to get rid of the clunk and help with bottom where iv already installed a DBO 650, so will an STM secondary work with my dbo 650 primary?
Thanx for any and all advice and tips in advance guys