Fuel consumption/trip computer recalibration? (1 Viewer)

[jsmithtaranaki]

Hi all long time lurker first time poster, sorry if I've done this wrong.
Recently acquired an 04 hundy 1hdfte 5 speed auto with stage 3 package (300hp) and is FUN
The trip computer reads as low as 7-8 L/100 ks but does 6-700 kms per tank and wondering if this can be adjusted?
TIA!