Since Mark II has a heavy body. I think the fuel consumption will be more with Beams and 7K then their consumption figures in the orignal bodies.
7K and Beams are generation aparts with 7K very basic engine compared to Beams ( Breakthrough Engine with AdvancedMechanism System) .
The best Pakwheel helpers of RWP/ISB used to be Spectra and Guncha but unfortunately they are not here anymore.
You can try Asif Electrician in G8.
As a rule of thumb you should always hooked up the ECL (Engine Check light) so that you can be aware if there is some issue with the sensors or not . Also is there any smoke or not from the silencer.