3ddino, this should be a easy choice for you your in Malaysia,the mvvs would be cheaper for you to buy wouldn't it? even on a pitts muffler i think the 58 is still stronger.there are reports of of 6800 on a 24-10 on a BCM side mount pitts.but you still haven't said what air frame your using. i would like to compare both with pitts muffler and same prop to see what shakes out.
if i would not have stumbled on the 58 for 400.00 i would have got the B60.if i would have put the DA 50 that i got on the shelf in the EF yak i would have been at 16-1/2 lbs. but i think i would need nose weigh to balance.so you do need to consider what air frame you are using.
ENJOY, LIFE IS TO SHORT!