so i was on the zpi site a few minutes ago and saw they had aftermarket pistons for xa/ xb. i was wondering what kind of horsepower gains i would see from these, if any?

 

A good idea might be to join the ZPI forum and ask on there.. they dont really get on SL much..
http://www.zeropointindustries.net/forum/

Im guessing gains would really depend on what other mods you have done and if your are gonna do any kind of head work also..

 

As Proshop said, just adding pistons isn't going to do much for you. It has to be done in conjunction with other modifications. Chances are, if you were to install either set of pistons (low or high compression) without any other modifications, you would be lucky to even get the motor to idle.

At the very least you will need some sort of engine management. Whether a piggy back would be sufficient or a stand alone is required is yet to be seen. As far as I know, no one has bought or installed the ZPI pistons yet. And you would definitely want some sort of forced induction with the lower compression pistons. Otherwise you would definitely be losing power.