If your looking at going external wastegated id go td04 or ct9 hybrid, i personly dont see the point spending money on replacing the mani for a standard turbo but yes id say they hold the boost better.
Just a quick update, my wepr kit got dispatched on monday so should have it tomorrow or monday, Also put a deposit down on a set of 4 pot wms brakes Happy days should have my car back a week tomorrow whoop