I used Tischer. The longer studs are only necessary if your new flange is a lot thicker. A lot of headers will not require new studs.
Also if you do a header install you 100% should also replace the O-ring on the constant pressure valve because they often leak. It is a 5 dollar item and a million times easier to reach when the headers are off!
https://www.ecstuning.com/b-ecs-part...iABEgKsavD_BwE