my friend just did an sti swap in his 98 rs. let me tell you... its not cheap. you have to send your wiring harness along with the sti harness to get it merged. that costs like a grand. you will need the the rear diff, and tranny. either the sti suspension or you can use the stock rs suspension. if you use the stock suspension, you will need to order custom axles from driveshaft shop. they are like 1200 bucks. we used the sti steering rack and crossmember, and steering column. you need the ignition, ecu, and immobilizer from the sti. i believe that they need to be from the same car or it wont work. you will also need the fuel pump controller and fuel pump from the sti as well. my friend has spent about 7 grand and its still not 100% complete yet. if you have any questions, you can pm me or check out nasioc.com or rs25.com. hope that helps