What you have now is very close to what my spec was before TTE
@Hookmonster
There are a couple of routes here and if you go down my chosen path you will need an Intercooler (I have an AirTech Stage 2 unit), TTRS LPFP, RS3 8V injectors, injector seal kit and modified injector wiring harness if you want to get the most of what the engine can offer short of forging it. Unicorn or R-Tech would be my choice for mapping as they both seem to know this sort of setup and are getting decent results. With Rs3 injectors I heard that potential power output can be higher than the other option.
Some say that you will need an upgraded LPFP controller, but I have not had any issues with the stock one yet - granted my system is not running at full capacity due to RS injectors not being installed yet. I'd hold off on upgrading the controller until you know that you need it.
The above is not the cheapest, but arguably the route that should result in best reliability due to the fuel system not running at or near full capacity. You could go down a significantly cheaper route and keep stock S3 injectors, but upgrade the RS4 valve to a 155psi or higher fuel return valve. This will allow you to run a much higher fuel rail pressure and force a lot more fuel through the stock injectors. This will allow you to run safer air/fuel ratio and make good power, but it is likely to also increase the load on the HPFP/cam follower, which will probably result in the cam follower wearing a lot faster. In addition, running stock injectors over their capacity may cause premature injector failure.
If you wish to go down the same path as me, then give
AKS tuning a call, who can supply the correct injectors, seal kits and wiring harness for around 600gbp.
The 600 might sound like a big outlay, remember that you can sell your old injectors for about 150gbp. The 155psi fuel valve is about 140gbp, so going down the RS injector route is not that much more in the grand scheme of things