Standalone ECU questions

[tmontague]

Can anyone who has installed a standalone ECU on a DBW throttle car please give me some input on the wiring.

If I wire in a standalone can the factory ECU be left with only the necessary connection ie: throttle and anything else it run other than the engine? Obviously a bunch of CEL's will be thrown but that isn't an issue. Or is it better to use a standalone that can operate a DBW throttle? In the near future when I foot the bill for thise I don't plan on cheaping out but I also don't want to pay a bunch more for a standalone that controls the throttle if the factory ECU does just fine.

This is new territory for me and I've read a lot but I'm looking for some real world advice for those that have standalones on their Yaris or have used them before in other cars. I have so far been looking at the AEM EMS 4 as it is optimised for 4 bangers, but I am open to other products as well. I already have AEM gauges so I'm somewhat leaning that way however.

Thanks