You have to have spark arresters, also some days they sound test. One day they sound tested my bike with T5's but my packing was bad and I hit 101dB so I had to pack it up. I bought a hush kit and some packing before I went home. You have to buy the stickers. The ORV and park sticker. Also a flag that hits the flag checker. You can get all this stuff at the park. I don't think Im forgetting anything. You have to pay to park to.
Edit: You have to have like a 94 dB limit they told me, but they accepted up to 98 or something. But in the years Ive been there, that was the only time they ever tested me and it was busy and late into the day.