Best place to start is ditch standard exhaust system,cat and front pipe and also fit pod filter (hks,apexi etc),boost can be increased on standard turbo to just below 1 bar safley just dont go above as have to worry about turbo/head gasket if u want to go further fit steel head gasket and drop compression ratio to run more boost and then fit bigger turbo,are u looking at changing gto for skyline then ?? they are great fun and you will love every minute any questions pm me
p.s i have 2 exhaust systems in my garage if u want one
Early (approx. pre Jan 1994) GTS25T's had steel internals in the turbo and are OK for boost up to .9bar, Later (approx. post Jan 1994) models have composite internals in the turbo and should be limited to .8bar boost or they will fail.
Thanks to you all for your help. The car has an HKS 2mm steel head gasket an HKS induction kit (green mushroom type) and a Nismo exhaust but still with standard cats. So I think I need a de-cat pipe and a electronic boost controler but I notice that not many of you seem to run these, why is that? also if I want a steel turbo and intercooler where do I go?
I am a HKS supplier as well carry the front pipes, de-kat pipes all 3 HKS exhaust systems on the shelf next day delivery if you require.
Give me a ring about the ECU we are HKS POWER WRITER DEALERS so we are able to supply and map on our new dyno www.dynapack.com the latest F-CON S ecu up-grade.