I have a T3/T4E 57/63 trim anyway i was wondering if i can use this flage http://www.atpturbo.com/Merchant2/me...de=ATP-FLS-032

The problem is this flange is about 2.5" opening while I measure mine is not even 2.5" its about 57mm ~ 2.23" Is there any gasket to used with this b/c i'm afraid it might leak. or is there a better fit on the DP flange?

 

You'll be fine having a gasket that is slightly bigger than your exhaust hole. You dont want a gasket that is smaller that will act like a restriction to the flow of exhaust.