[rotrex]

With so little flow, I would not worry about modulating the flow. Just activated it when you hit some boost level.
In order to really do something, you should try to increase the flowrate significantly to like 25% of the fuel flow. You will need to retune your ignition timing.

I would also install a bigger turbo on that VAG 1.8T. There are plug and play compatible turbos on the market. A T04 sized turbo can easily push you into the 250 to 300HP territory. These engines will take that all day long without any upgrades required.
Just ensure that the coolant is always flowing and the thermostat works properly. If you stall them on a trackday, you may distort the cast iron block.