Looking at the other thread on here about the MEFI IV has me wondering what the advantage would be to updating from MEFI 3 to 4. I have a ramjet in my car now and it runs just fine but the price of $450 approximately for a controller and wiring harness seems reasonable if it actually makes an improvement. Has anyone made this change or know about the benefits i.e. more horsepower, torque, better mileage.....whatever? Also does it use a single O2 sensor?