The DSE connectors require cutting the floor, but if it is installed carefully, it will look like a factory job. I've read that the cars vary, and the template can cause you to cut your floor in the wrong spot. So if you're going to cut your floor to let in a connector, take nothing for granted and make your own measurements.

The Hotchkis round frame connector doesn't require floor cutting.

There are other choices out there that don't require cutting your floor. Some weld, some bolt up. Some can be modified to bolt up those designed for welding.

The DSE looks very nice, but its a big decision to cut into a factory floor.

At that HP level, you need some sort of connectors. I've seen stock birds with stress cracking in the quarter. Five hundred plus horse is bound to tweak the car if you hook up and have no connectors.