Quick question about the effectiveness of some mods

[coopertrooper]

Hey guys my first post here!

I drive a 1990 Nissan Skyline GT-R (RB26DETT) I was recently informed that a de cat straight through exhaust with manifolds, an Apexi E.C.U with an air filter and cold air feed, Blow off valve, boost controler and sports intercooler would net me around 400 BHP.

Is this true? And if so what sort of torque figs can i expect with that?

Thanks in advance for any info you might want to give!