Who knows about exhausts?

[Nostromo]

So heres what I'm faced with:



Its not actually a picture of my car but its pretty much the same. So the manifold leads down to the right hand side of the cat, goes left, up and right into the backbox then back out and down the left to the tail pipe.

What I want to do is leave the cat in place, then bring a slightly larger bore pipe up, to the right, down and out and in so doing, deleting the backbox for a bit more noise.

Will I face any loss of power/torque?

Will I benefit at all from using a slightly larger bore pipe? The only reason for a larger bore is I guess less restriction and a more aesthetic/pleasing look where the tailpipe will exit.

Any help is much appreciated