Can i, or has any one installed a walbro 255 to there S4? It seams crazy to spend $500.00 on a RS4 Pump if the W255 can be attached to the stock housing.

 

I have a walbro on my stage 3 setup. On my new turbo setup I have twin in tank walbros.

Stock pump is fine for most stage 3 applications. Unless you have a bad FP or plan on running E85 then you probably won't need a walbro.