Now that the chassis and brakes are dialed on the S4, the next thing I can improve is seating. There’s two ways to look at it. First you can improve your seating position, and second you can improve safety. Currently my standard operating procedure at the road course is to slide my seat all the way back as far as it goes, lock the seatbelt with my wrist, and then slide the power seat forward until the shoulder belt is crushing my chest. This is the only way to brace yourself without a 5 or 6 point harness. Other than using your left leg, which is a bad idea for a number of reasons. The ideal seating position is one where the car is tossing your body around like a dead fish but you don’t move far because the seat and harnesses strap you in. Then you’re free to feel the wheel and chassis rotation.
Regarding safety, you can go to a HANS compatible seat (head and neck safety device), which is a brace that attaches your helmet to your shoulders to the seat. The problem is these seats have wings on the side (for side impact crashes) which make the car impossible to drive on the street because visibility is obscured. Fortunately, Sparco makes a seat with removable side wings for $1000 called the Edge. It weighs about 25 pounds with the frame rails. They sell a pure carbon seat for $3500 that weighs 8 pounds (15 with rails), the S-Light.
Sparco competition seats might be overkill. In the OEM plus category, there’s the Recaro Sportster CS. You can order these in red alcantara inserts as standard, or custom order them in red nappa leather for some extra cash. They’re about $2000 a seat all in and weigh about 30 pounds with the rails. Figure double price for the nappa leather to match Audi magma red.
Of course to use a multi point harness with these you need a roll bar installed in the back seat. TC Design in San Jose does the best work in the business on these. They weld a custom tube assembly, and can make it bolt on or weld it directly on to the chassis.