Your knowledge on Supercharger upgrades

[Born_2_Kill_83]

I have seen an up rated Crankshaft pulley for sale including the belt. This is meant to give around additional 40BHP.
Question is, will any ECU alterations need to made upon fitting this or is it a simple plug and play (so to speak).
Considering this as a cheap upgrade to get me over 400 horses. But I’m not fussed enough to spend more money getting the ECU remapped, the difference I doubt wont be very noticable

 

[Born_2_Kill_83]

No its just plug and play, the ECU adds the correct fuel for the increased boost. I assume this is an XJR is it?

Yes, how much decrease in fuel consumption will there be?