Larger boost valve. The stock is a .471. I used a .500 which is a common 700r4 piece. There are also .555 and .570 pieces out there to really jack up the pressure. I have read about a .521 and a .530 but have never seen either for sale. You also need the 700 spring and I did a larger rev boost valve too.
Also setting the clutch up with a tight clearance is highly reccomended. I was told .007 per clutch which works out to .040-.050 for the whole stack. Juggling thicker steels and such can get you there. Some go to a thinner clutch/thinner steel to get more clutches in but I went with the stock count red clutches and thick steels to absorb the heat and a tight clearance to minimise the slip that generates the heat. The red raybestos stage 1 clutches for the direct were one of the things I spent extra on as I didn't want a 2-3 problem. I put Borg warner tans in the rest except the carbon band.
If you have a billet shaft forward drum dual feeding the direct is probably the best way to go.
David Husek or one of the gurus will surely have more info.
