which is better. 2 piece bars or 4 piece bars. i used to have a 4 piece but recently i bought a 2 piece.

It's not that simple a question, some 2 piece are stronger than some 4 piece and vice versa.
What you need to look at is how thick the tubing is(thicker is stronger) whether it's butted(butted is stronger), and how sharp the radius of the bends are(sharper bends are weaker), and the material(41 thermal is stronger than regular cromo).

I don't know for sure but I'd imagine something like the Scerbo bars and the odyssey butted 41 thermal bars would be strongest, closely followed by an S&M bar with the dual radius or one of the other butted bars.

2pc.

2pc

2pc.
Made by either:
S&M
FBM
Odyssey
or
Animal

i like fly bars personally

3 amigos.. nice bars

yeh, ive got the mosca bars

gary young's and civillian svelte bars are also very nice.. haven't heard much about the Macneil Lighter bars.. but I'd imagine they are pretty nice as well

or the new fit flow bars

I'm running Macneil Tall light bars.
They're silly light, but so far have held up great.

I'm running Macneil Tall light bars.
They're silly light, but so far have held up great.
Yeah, I think those are the lightest bars out there (for their width, otherwise they are tied with the 3 amigos)... but they are heat-treated so I'd imagine they could hold up pretty good.

Added some information

Fly bars = cutting your grips, and running the lever on the bend (thats stock, wait till you cut them...)

Just get some S&M's or Fit Flows(i want a set..)