DID WANT TO MAKE MENTION ABOUT SOMETHING...i have a jet chip on ebay starting bid at 75 bucks...buy it now at 175.....i put it on our classifieds...in case someone was looking for that item.
Sam, I wouldn't say anything in your sale thread, but when you post it here, it is fair game. That product is a worthless scam (by the manufacturer, not you) and will do nothing for a Kappa. And that has nothing to do with what the OP was after anyway, which is info on a specific engine transplant, not snake oil. Those piggy back units that plug in between the ECM and the harness and try to manipulate signals more often cause problems than not and almost never do any good. A simple tune will get whatever is there to be gained (unfortunately on an NA nothing near what Dan is after) without any fuss.
Dan - the Northstar had some issues but the design is nice - quite a few got shoehorned into Fieros. Beware the territory it takes up, as jwvess00 said - they are a WIDE engine across the top end and there may be fitment issues.
I agree with the guys that said that a GXP would suit your needs. Unfortunately, selling your NA and buying a GXP would probably get you more than a $2,000 differential unless you were very lucky indeed.
OTOH, thinking you could stick a different engine in your car for only $2,000 is naive in the extreme, so the GXP might still be your best bet as you'd probably spend that differential anyway if you embarked on a swap project.