Here you find some dyno sheets of the Nissan GT-R R35 with different tuning stages.
First run:
Stock, according to dealer specs 485pk
Measured : 511 pk and 637 nm
 Dyno GT-R R35 stock
Second run:
HKS rvs cat-back system
Measured : 533 pk and 663 nm
 dyno GT-R R35
Third run :
HKS exhaust and K&N replacement filters
Measured : 536 pk and 671 nm
 GT-R R35 dyno
Fourth run :
HKS exhaust system, K&N replacement filters and Cobb tuning
Measured : 616 pk and 757 nm
GT-R R35
Fifth run :
HKS exhaust, Cobb tuning ánd Switzer P800 kit
Measured : 800 pk and 900nm @ 22.4 psi (highest boost on dyno), on the road we drive @ 24.5 psi which gives about 840pk and 950nm.
GT-R dyno run with Switzer P800 kit