turbo upgrade n00b, t3/t04e efficiency?

[ANVIL]

so i finally got my setup pretty close to ready to go. ill be making an appointment within the next few weeks to get my car dyno tuned. basically its a stock s1 rb25det, upgraded to a t3/t04e 50/60 trim garret turbo with 650cc injectors. im shooting for around the 400whp range... but im wondering what is the highest/safest + most efficient boost level to take it to? im not sure what to tell my tuner, or if he is even familiar with the turbo. he exclusivly deals with HKS turbos and doesnt do very many other private tunes. my last tune he let me decide on how much boost to run on my stock turbo so im not sure what to tell him on my upgrade

[Cjmartz2k]

Just keep turning it up until it (a) knocks or (b) won't hold boost anymore. I'm guessing the latter will happen first either because the exhaust side on that thing will strangle it, or the compressor just can't feed the motor. I had a full TO4e once upon a time and it would open the wastegate around 1.5 bar, but would fall down to around 1.2 near redline. Just not enough compressor for a 25.

Start at 1 bar and inch it up from there. If it knocks and you already pulled a bit of timing out of it, turn it back down a bit and call it a day.

[ANVIL]

i guess that makes sense. i guess thats what hed probablly do. how much whp were u pushing with yours?

[Cjmartz2k]

It was a dyno jet, so take it for what it's worth, but 399.5rwhp

[ANVIL]

what other mods did you have at the time? what oct gas?

[Cjmartz2k]

Off base Hi-occu which is 106 RON. I think that's like 96 octane in the states. I would set the boost for like 1.5 bar, but it would fall down to 1.2 bar by redline. The motor/intake/cams/HG, all that was bone stock. Just supporting mods and the turbo kit. Remember though, it was a full TO4e, not a T3/TO4e.