how much bigger can u get the 3.1 bored over and do u need to get bigger pistons, and how do they increase the stroke
 
look man you need to get a book on internal combustion engins and study it!
to anser your question yes if you bore out an engine you need to get bigger pistions 
and no this has no effect on the stroke 
the stroke is a hole nother ballgame
 
 
 
Well..as far as I know, u can get a 3.1 bored .10,.20, or .30 over, i'm gonna eventually b getting mine bored .30 over. U can't really go anythign more then that, cuz of the cylinder walls...
 
as far as i know you can't really increase the stroke as its pretty much maxed out already in a 3.1 (if you break the timing chain you will bend valves 
 
 
well if i get it bored .030 over will i see a difference and if i do get it bored over i can buy stock pistons bored .030 over to right
 
.030" over isnt a lot. you wont notice any gains from it.
you can buy stock replacment pistons in .030 over. however, if you are rebuilding a motor for performance, get some higher compression hyperutectic (or forged) pistons.