I suggest a SAFCII or AFC neo and a wideband. Very cheap tuning solution, very easy to tune. It will help you get the most out of your other bolt ons. You can lean your A/F ratio down to 13.0 on an N/A application, but I would only go as lean as 12.5.
If you have a shop dyno tune the car for you you don't need a wideband, because they will have one hooked up to the exhaust. If you do get a wideband, you can easily tune a SAFC yourself. Extremely easy, seriously. You only would use a shop if you are using a reflash, full-standalone, or something much more serious than a SAFC
I'll give you a basic idea of what it does, if you want more info on installation I will be glad to help. A SAFC is a very basic, but effective tuning device. It only modifies the maf signal that the ecu sees, therefore you can tune how much fuel your ecu adds. It adds or subtracts fuel on an RPM basis.The wires you tap into are:
I have my neo set up to display RPM (the exact number), Throttle percentage, and Battery voltage. There are a few cool ways to display the data like digital and analog gauges. You can also have any color combination you want.
If you want to tune yourself you will have to get a wideband to show your A/F ratio (I highly suggest the AEM UEGO, very accurate, pretty cheap). All you do, is have your friend hold a video camera so it can see the RPM gauge (factory or SAFC) and the wideband gauge at the same time. You do a pull through one gear (third or fourth). Look at what the A/F is at each 500 RPM increment, and take fuel away at that RPM till your wideband shows the number you want all the way through the powerband.
alright, yeha i was lookin at the AEM gauge, both are great price wise. im just waiting for the header to come out before ordering the neo and gauge and pulley. and you said for a ratio 13 shouldnt be too lean?
Good choice on waiting for a header. That's probably going to be the mod that most benefits from also having a tune. In an N/A application 12.5-13 is going to make the most power. Just cruising around your car should automatically be close to 14.7, but when you are WOT expect much richer numbers. Mine was at as rich as 10, but every car is different.
I would still recommend tuning only to 12.5, as you are probably going to be a pioneer in tuning a Versa. We don't know exactly how the ECU is going to respond to a fuel controller. Being a Spec-V driver, I have had many people before me to figure out exactly how the ECU works (like when it goes in open-loop and closed-loop, and how lean you can push the car, N/A, supercharged, and turbocharged) You don't need to know all the specifics unless you are going F/I though, so don't worry about it.