I used studs and I wouldnt do it again on a non race engine. They are a pain in the butt to get to seal. I used good (arp) studs and there recomended sealer and still had a few leakers. I ended up using a permetex product and finally got them to seal. I dont have the space issues in my tbucket but in a car with fenders I guess they could present some space issues as well.