What altitude are you playing at? When I go play at Lake Tahoe. I bring understable stuff or lighter weight. A Valkyrie was as overstable a disc as I needed. Or if you have discs in the 160ish range, you should be fine. It was kind of funny watching a Valk fly like a Teerex!
For a reference, I throw around 300 to 330'...Have fun at the tourny!