I would like to know what a stock S4 turbo is capeable of boosting to. what PSI . and what mods can be done to them ?

 

On stock fuel? Leave the boost alone or take it ONLY to about 8-9 psi max. You go over that, and it will pop.

Mods are endless, so I'm not going to list everything (obviously). Search and you'll find anything and everything. But some basic things you should consider would be porting the wastegate (http://fc3spro.com/TECH/HOWTO/ZWG/zwg.html), getting an aftermarket exhaust system, getting an Rtek stage 1 chipped ECU (www.pocketlogger.com), a better fuel pump, some bigger injectors & a good boost controller.

 

Ok I understand that, I was refering to the turbo. How much can you get out of the stock turbo units ? My motor is modded and brand new and built to handle 1 Bar of boost . But I want a street driver. I just want to know what the stock turbo unit is capeable of.

 

~12psi before pressure increases start to build up way too much heat. The life of the bearings will decline quickly if pushed beyond that level for long.

 

I think I'm going to take your suggestion on the rtek. running 550 cc primary and 750 cc secondarys, Should i look at the wastegate ? should I go aftermarket or get an S5 wastegate and port it, and can that work be done while the engines is in the car ?

 

You can't buy an aftermarket wastegate for use on a stock turbo (without custom fabrication). The stocker uses an internal wastegate; take a look at the porting link I gave you before. The turbo has to be removed to port it, so you may want to pick up a stock S5 turbo & exhaust manifold, port it, then swap it on the car.

Oh, and if you intend to run more boost, the most vital upgrade is the fuel pump. An FD pump works very well, and walbro 255s are another option.

 

http://fc3spro.com/TECH/FM2W/power.htm