dx gti 4-2-1 exhaust manifold

im looking to fitting a stainless 4 branch manifold and system to my gti, does anyone know what sort of power gain i will get from this and the optimal way to gain performance with out a high lift cam which i may fit anyway!!

 cheers  

In my experience you will not gain any power that you can measure. you may think it faster as probably be slightly noisier.

yes thats a valid comment!!