I have 05 Jdm sti with Twin scroll turbo,equal length headers and a uk fuel remap for V-power and still the standard Jdm exhaust system its got 328bhp and 327lbts of torque at 1.35bar going by delta dash dyno run .03 onwards have the twin scroll turbo ,equal length headers set up.It was mapped by Andy Forrest Peformance.Don't know what power it had before but big improvment in torque and power in the rev range