Update:
Pick up a new turbo to test with my monster BW S475.
New high pressure turbo:
DSM 68HTA
Compressor wheel - 68HTA
Flow rating - 51LB per minute
CW Measurements - 51.2MM Inducer / 68MM Exducer
TW Measurements - 60.8MM Inducer / 54MM Exducer
Compressor Housing - 16G TD05H
Turbine Housing - FP 8CM
CHRA - FP Journal Bearing
Pic
Low Pressure turbo:
BW S475
Compressor wheel - 75 mm ETT
Flow rating - 100LB per minute
CW Measurements - 75MM Inducer / 100MM Exducer
TW Measurements - 96MM Inducer / 88MM Exducer
Compressor Housing BW S400SX4
Frame T6 with a 1.32 A/R
CHRA - BW Journal Bearing
Pic
This combination has be tested and proven with a fellow DSM Talon friend that has gone high 7's at 180mph in the 1/4. He is one of the pioneers in gasoline turbo compound systems.
Here are some data-logs from his runs showing great back pressure numbers.
Back pressure log
Awesome engine delt p numbers as the gates open to bypass around the high pressure turbo!!!
For me HP performance will always be in my blood so the more I can make the better, but I think this combination will help also with back pressure issues at light load and help with FE.