Pistons (9.25:1 Compression Ratio)
Cars destined for the UK & other countries where high octane fuel was available were originally fitted with 9.25:1 Compression Ratio pistons with part number UE31258 stamped into the crown of the piston.
If you are unsure which piston your car has then the part number is stamped onto the face of the piston along with its grade
S grade is equivalent to H & J grade | T grade is equivalent to K & L grade | X grade is equivalent to M & N grade