I use a 4 point I brought from eBay. Lap belts are bolted to existing lap belt points along with stock belts and shoulder straps go to 2 brackets between upper and lower rear seats which I presume are for child seats? Had to use a couple of small shackles. When I'm at the track I just leave the stock belt around behind the seat and plugged in. Or just use both! The harness is definitely helpful but if you don't get it tight it comes loose. Yes a seat would be nice but i'm trying not to mod the car that much. Also if they did have an issue with a harness and stock seat you still have the stock belts.