>>13730732ex race chassis fabricator here (Baja shit back in the day)
You want your seat and seat belts tied into the same structure. If you have a roll 'cage' like a full 6 point, you want your seats tied into that structure and your belts as well. If your seats are tied into the original chassis of the car, you want your belts there as well.
Also, don't sell 3 point belts short, they're better than you think. if you want to go full harnesses then you need to go full 5 point with a full seat tied into the roll cage with belts tied into the roll cage. harnesses in street cars are for posers.
