What can I expect from a magnaflow exhaust?

Honda Civic 2000 lx
B18c vtec DOHC swap (and all the corresponding parts like the manifold)
AEM cold air intake
But I have a stock exhaust pipe.
I recently purchased a magnaflow exhaust with 2.25" piping and I would like to know how much hp I could be looking at gaining, now I m also well aware that in some instances there would be little to no gains at all. But I read that for upgrades on stock civics. Any help? Just curious

Read more: What can I expect from a magnaflow exhaust?