Both the mounts for the trunk lid and edge of the seat back are attached directly to the inner wells. Using a chisel, drill, and cut off wheel, we were able to persuade both from the wells. Be careful as you will be reattaching both once the installation is complete and don't want to damage anything, especially the trunk mounts. Don't be afraid to jump in the trunk if need be to get to the hard-to-reach places. Just make sure no one is working underneath the car when you do so.
The supplied CD contains a printable template for making your cuts and creating patch panels. This comes in handy as it will all but eliminate much of the grinding and cutting that would need to be done if you were to cut the wells out free hand. The new DSE tubs will mate to this cut line awfully close, which is why it is a good idea to follow it. Place the template along the wheelwell accordingly, make your marks with a magic marker or chalk, and get to cutting.
If you have a plasma cutter, this is the perfect time to blow the dust off it. A plasma cutter will drastically reduce the amount of time it takes you to cut around the well. If you don't have one, a cut-off wheel will do a great job. Make sure to wear eye protection as sparks will be bouncing off every corner of the trunk. One way to attack these cuts is from the trunk and we found that to be most effective. Another way is to work from the back seat as the seat back has a bunch of giant holes in it from the factory.
Along the way, we made sure to take several measurements from the framerail to the outer wheelwell and from the outer wheelwell to the trunk so we know exactly how far we need to make our cuts into the trunk for the new tubs, and how much to cut out of the framerail. We know that the new tubs will sit almost flush with the outward edge of the framerail, a whole 2.5 to 2.75-inches further in than the factory tub, which is where you get the added space from.
Now is the best time to notch the frame and make the template of the new sheetmetal we will need to be installing. The factory framerails are not straight from front to back and bow out as they reach the front upper corner of the wheel. Our frame notch, in a nutshell, cuts into the framerail and eliminates the bow that would ultimately rub out 315 tires. Here, we cut out the notch following the template.
Using a piece of 1/8-inch steel as recommended by DSE, we made our new piece using some sheetmetal, bent it into shape using some manpower, and tack welded it into place. The 1/8-inch piece of steel is essential to maintaining the rigidity of the framerails even though we basically eliminated more than half of its thickness.
It is now time to slide the new DSE wells into place and see how close our cuts are. Once we found about where the tubs were going to stay, we clamped them in place and ground down some of the uneven edges from our earlier cuts. DSE recommends using spaced tack welds around the wheelwells while making the connection to ensure the metal does not warp in the process. During welding, the pieces of metal can actually become so hot that they lose their shape.