what are the advantages/disadvantages of stroking out a motor to a higher displacement, i see alot of people do this (especially american car guys) and i'm curious what it accomplishes

 

The main advantage is a longer stroke which means more torque/power. A major disadvantage is the change in rod/stroke ratio.

 

roughly how much of a power/torque gain is it?

 

http://www.importreview.com/dyno.html

 

that's got some cool charts but i don't see how it helps answer my question much?

 

The main disadvantage of a stroker kit is that the larger the displacement the thinner the cylinder walls/sleeves will be. Example: Most engine builder's will only stroke a 1.6L to 1.8L if it will be used for turbo/nitrous applications. This also helps ensure the cylinders do not "float".

 

How does a stroker kit make the sleeves thinner? Are you perhaps thinking of boring the cylinders(which also increases displacement)?

 

more stroke = more piston speed = lower redline