Handbrake on, and follow the Lotus handbook instructions for jacking the car and for the placement of the four axle stands to elevate the car safely for work.

With the car in the air, make sure the side sills — and in particular the underneath of the sill are clean. Double-sided tape is used in later steps, so a clean surface is essential for a good bond.

With the car clean, position the extended side sills for trial fitting and for marking the drill points in Step 04. We found the best method is to apply three pieces of double-sided tape (front, middle, rear) to the extended sill, so you can press it into place, trial fit, and mark up before any final drilling.

The design gives you plenty of room to extend out from the side of the car, depending on how aggressive a look you're after. We found a nice balance at around 55mm from the body at the front (aligning to the front mud flap — Figure 2) and 40mm at the rear (Figure 3).

Once you're happy with the final fit (Figure 4), with the extended sill temporarily held in place by the double-sided tape, mark up the drill holes underneath with a marker ready for Step 04.

Once you're happy with the final appearance (Figure 4) and have marked up the holes underneath (in Step 03), remove the extended side sill from its temporary double-sided tape fixing.

You should now have six markings underneath (Figure 5) — these are where the supplied riv nuts will be installed for final fixing of the extended sill.

When ready, install the riv nuts using your preferred nut-riveter tool. We use the Sealey short-arm tool, which we've found handy given the small working area underneath the car.

With all riv nuts installed (Figures 7 & 8), you're now good to bolt on your extended side sills using the supplied washers and bolts (Figure 9).