my brother is rebuilding a vl turbo engine and has a hiflow t03 turbo which has the standard wastegate. he also has a 300zx intercooler and was wondering if it is ok to run it in with no cooler. once it is runin around 1000kms he will then take it to have the cooler and piping fitted. how much boost can he run with no cooler? how much boost can he run the hiflow on with a 300zx intercooler? also he said there is a small hairline crack near the wastegate flap of his rebuilt turbo, is that bad for upto 12psi or not realy?

The hairline cracks are pretty normal on these types of turbos, because of the faulty housing and wastegate design. I suggest that you run it in on about 6 psi boost for 1000kms so that everything beds in with no problems. Use a good quality mineral oil - othewrise you will get a lot of problems wtih the rings bedding in and heaps of blow by because the synthetic oils contain friction modifiers that hamper the bedding in process. Boost is a function of tuning. Also 12psi on a highflow is not the same as 12psi on a standard turbo. The maximum boost you should run, or any boost change as a matter of fact should be determined on a dyno with an experienced tuner and an AFR Gauge. My dyno tuner can hear pinging and i cant hear jack! It pays to get everything tested out so that you can be sure that everything is 100% in working order.