Its an RZ, anyway back on topic
If the turbos can flow "theoreticly" 300hp each you would have to run them at max efficiency to reach the said 300hp. Thats "if" the manifold and down pipes can accommodate this, which they cant.
My turbos can flow 410 bhp each but that doesnt mean my car can run 820hp and HKS are very conservative with their figures. My car is also running the downpipes and manifold to match so no restriction.
Just because they "say" the turbos will flow a said amount it doesnt mean they will in this application. Lots of people on here have run the hybrids and have dyno print outs to confirm the results. When you have yours you can coment.
Lee