i want to put a twin turbo set up in my z. it came down to aps and greddy 2 most affordable, dont want THAT much hp 350-450 is fine. but how come it says to run a aps set up safelly at 8-9psi but greddy at 5-6? are you supposed to ahve a built engine for aps, cuz i kno people who dont and run fine on 9psi. i apreciate the help.thanks

 

You dont need a built engine for the APS at stock boost settings..

 

The aps includes things the greddy doesn't


EMS and Fuel system w/injectors being the most notable

 

Greddy comes with an EMS-not a good one, but the Unichip is not great either. Both are excellent kits, but the more complete kit out of the box is the APS. If you want a tuner style kit you can add your own EMS/fuel system to, then do the Greddy.

 

I was in the same boat you were, on the issue of "safe". Sure there are lots of stories of boosted Z's on stock motor being safe. But there more stories of stock motors blowing than built ones. I decided to spend the extra money and build the motor now rather than have it blow latter. I will have way more piece of mind and more more HP!!
Thats not to say that you can't be safe on a stock motor, @ reasonable levels, there are 500 stock blocks (see MRC) who really knows how safe, its just a chance you are taking, the only way it decrease the chance of engine failure is built a motor.
BUT if your goal is 350-low 400's you should be Ok, in that case APS its just better all around I
think.