cut the tray floor out of mine. Removed rear end assembly and supported rear of car by cutting a hole on either side of the cross member. Slung a fibre sling through it and hooked onto an electric gantry crane. Using a 5mm drill bit, followed the chassis rails and cross member lines, drilling holes every 50mm. Lowered the car back down again, using holes drilled through top of tray floor as a guide, cut the tray floor out in sections. When it came to chassis rails and cross members, used flapper disc on a 5" grinder, grinding till spot welds have been located and ground 90% back. Pair of pliers is all it takes to pull of the rest, ensuring you dont weaken the rails and cross members at all. Went for a 2mm flat steel floor in mine. Bear in mind however that the existing fixing height for the old tray floor is 20mm higher than the top lip of the rails. SECOND floor attempt had ends pressed up at 45-degrees, approximately 25mm from the edge. Inner wheel arches are rolled 2mm flat steel also. Fuel tank rear mount is fixed to the underside of the tray floor. Retain the mount from your old floor, bolt the fuel tank up to the front mount and mark location for rear. Also have to cut out access panel for fuel gauge sender wiring. Dont know about strength opposed to factory pressed tray floor, but certainly adds a bit more weight over the rear tyres.