ive been using braid for a little time now on my shimano stradic and my ive been using 8# stren as a base before i put on the braid my question is does adding a mono backing help or make it worse for the braid overall in performance 

You have to use a backing line or the braid will spin on the spool.

The backing should not effect the performance one lick, provided you put adequate main line on and are not casting far enough to eat into your backing.

yeah it works ok the only thing i noticed lately with it is getting loops in the braid on the spool nothing serious just really annoying 

Make sure to close the bail manually and don't start retrieving until there is tension on the line near the spool. I just found out that last part recently and it has cured a lot of line twist/loops for me.

Backing doesn't affect the braid's performance. I use cheap mono as backing and leave room for 50-60 yards of braid.