i know how its done, but dont try it yourself, has to be on a cO machine as its really sensitive

its the fuel pressure actuator on the side, little black box, some tuners can do it, for around 80 - 100 quid,

Mine ran lean on full boost at 21 psi,on a road lambda check, had the fuel pressure mod, sorted it out,

You will now get people on here now say it makes the car very bad on fuel and has bad econmony off boost, but for one thing, i get the exact amount of miles outta of a full tank of fuel as i did before i rebuilt my engine, and only running 14psi.

I not saying the fifth injector is a bad idea at all, if i could afford it i would install a mf2 one, but my tuner done the fuel pressure mod on mine at my car goes right off the clock with no pinks or hold backs at all, on my rolling road power run at the weekend my graphs curve line was very smooth.

there is a cold startvalve 5th injector out, what people are now going for, which is 125 quid, never used it so cant comment

Hope this helps