Trust t618z for r32 gtr

[khezz]

Hi all this is my first post. I live in Perth Australia. I am debating on a turbo upgrade. I just want to know if any of you have any info on the trust twin turbo kits. I was looking at the t517z and than saw the t618z on the list. How much more power do they bring and are the much laggier than the t517z.
The rb26 has all forged internals and 264/9.5mm cams. 800cc injectors with the power fc d-jetro thus i dont have air flow metres any more. The kits here in OZ are almost the same price. My goal is as much drivable power as possible. i know that t517z will give me about 550hp at all fours and still be responsive. Any reviews will be welcome. thank you