This is a better solution because you can not play with ECU and you can not upgrade its software as well. Only Suzuki can do that but they don't have any such software upgrade yet. All you need to do is drive for few days with direct purge hose into throttle. Check the exhaust and observe if there is any black smoke. Observe the average per liter etc. If everything appears fine then this is the optimum solution from our end. Shitzuki could not even figure out the problem in 4 years. That's how much dumb and stupid there mechanics and engineers are.
Other solution is to drill a thin hole in fuel cap or change the fuel cap with after market one which is not air tight.