Milltek Hi-Flow sports cat and downpipe is one of the most important parts when tuning a turbo car, it frees up the air flow from the turbo and allows the turbo to get rid of the spent exhaust gasses more efficiently reducing temperatures and allowing for more head room for the turbo to make more boost over the stock part.
In our opinion the downpipe is the most important part of the exhaust to change as it makes the biggest difference. This is why there are options to marry the downpipe up to the stock cat back system. This is becoming more common and still sees very good results.
Stage 2 software is a requierment for a hi-flow sports cat and downpipe.
There are a few option depending on which car you have.