who's using fuel trim controllers?

[jiggersplat]

i'm talking about things like an like an AFC or map-ecu or HKS fcon, greddy e-manage, etc. one of these things plus a wideband o2 sensor could go a long way. when i get in my other car we use these things for more HP. but it all boils down to efficiency. i see no reason we can't use these things for improved fuel economy.