Buy it from David at seremotors on this site for £9 delivered. If you can find a cheaper price let me know! Just remember to keep it in your garage and NOT the car as it does stink!!
I've just doubled up for the 1st tank of fuel and it says after about 250 miles you should start to notice a diffence. I've now done 275 miles and definitely more sharper, less smokey and smoother through the gears!
A great investment!
POB
Alhambra 2006 140 TDI Stylance