Ok here is some good info we have developed of before and after on the 2015 hellcat A8 model
Bone stock the best pull was
614/588
And modified was
760/745
+146 hp
+157 tq
Modifications are as follows
Craven Performance & Off-Road LLC CAI
Upper pulley combo 13.5-14 PSI
Long tube headers
Meth system
Custom calibration with HP Tuners
Catch can system
METCO MOTORSPORTS
American Racing Headers