Here's a dyno graph of a friend's '98 UK spec WRX running the HKS GT2835 turbine. The car is near stock except for HKS EVC IV boost controller and HKS Type S FMIC. At the time of dyno, the car was running only stock 380 cc/min injectors and stock fuel pump. Imagine the same turbo fitted to a US spec 2002 WRX running STi 565 cc/min injectors and big fuel pump, running 1.3 kg/cm² boost, OH MY GOD!
http://dyno.scoobynet.co.uk/uk/nito_morelli.htm
Looking at a turbo review by HyperREV Impreza No.3, The GReddy TD06L2 20G-8cm² turbine kit produces 357.4ps @ 1.2 kg/cm² and 383.5ps @ 1.4 kg/cm². According to the 1.2 kg/cm² dyno graph, the TD06 turbo starts to spool as low as 2000 rpm, feels the kick at 4,000rpm with boost peaking at 6490rpm. Power is sustained till 7500 rpm before the curve takes a dive.