also like FC3Cturbo posted, make sure that all your sensors go with your series motor. n374 is the code for s5 jspec turbo models.
series 4 compression 8.5:1
182 hp 183 tq
series 5 compression 9.0:1
200 hp 196 tq
the turbos them self are different as well. the series 4 used a twin scroll actuator that would be closed in the lower rpm to help boost and would open when in the higher rpms.
also the rear ends are different types of LSD. the series 4 is a clutch type and the series 5 is a vicious type. they both have the same bolt pattern for the driveshaft and halfshafts so that doesnt matter.
also get on rx7club and start searching. their are tons of people that have done the swap and dont just post asking the question search or you will get flamed.