I have to say that it IS possible to have an RST that is reasonable on fuel, of course it depends on what spec it is.

Mine has an Omex 710 Series ECU and 525cc Injectors. I see over 200 miles to a tank-full without any problems and that is at 350bhp. I am quite pleased with that. Haven't worked out MPG, but it must be close to 18-20 on average, which at that spec is fine.

This is because alot of time has been spent working on the off-boost and driveability mapping. This is something that takes time and costs money and is only as good as your management system allows versus the time spent setting it up.

K-Jet is thirsty if you are running high power and the only real way to get any level of economy is to run a 5th Injector, so that you can have sensible off-boost fuelling and chuck extra fuel in when needed.