The export version of the
2JZ-GTE achieved its higher power output with the use of newer stainless steel turbochargers (ceramic for Japanese models), revised camshafts, and larger injectors (550
cc/
min for export, 440 cc/min for Japanese)
remember this, the jspec 2jz has a lower stock hp rating than the usdm 2jz. so your starting off with a lower power motor, so you need more upgrades to boost your power levels up. as the jspec 2jz uses ceramic turbos, ditch the twins for a large single and put bigger injectors in.