Easy swap. Move the motor, trans and passenger axle over. Keep your existing wiring harness. Add the boost control (or run to air) and change the connector for your map sensor (or buy an L32 one, same connector as the L36). Use the 99 GTP pcm to run the car while you have someone program you a 98 GTP PCM with your VIN in case the car ever needs to be emission tested or scanned by motor vehicle dept.