dattoman, you can buy an assembled megasquirt off the manufacures, i cant remember prices from years ago really but it makes it roughly $600 instead of $400. No point anyne here trying to put something together when that is already available

I'm a technology doofus... so wouldn't know which one to buy anyway

$157 for a ECU ? Why would you bother with such a piece of poo ? I may be missing the point a bit and I apologise in advance if I'm not on the same page as you guys but isn't the whole reason to go efi is to improve the induction / ignition systems ? Is that ECU tuneable ? Does it have logging? Wide band lambda correction? Sorry can't see the point.

Yes wards at that price it has all of those functions and will control spark as well. The only thing with buying one at that price is you will have to build it.
I'm not saying its the best way to do it BUT we are talking about doing it cheaply and for an EFI system it is cheep and good quality. I'm currently using an ms-1 on my turbo l18 and it works vary well and although I'm upgrading to an ms3 pro for the sequential fuel+spark and on off functions my ms1 will still be used on my turbo a12 with fuel and spark.

For more info on ms go to this site. http://www.diyautotune.com/

Megasquirt kits can be had for $150 used and are very very good, tuneable, programmable for use with or without O2 sensor. And tuneable for max fuel economy OR max power.

Datsun ECUs can be had for even less money and run well. They are not programmable but will adjust to different size engines in stock and mildly upgraded tune.

Lambda (O2) sensor is primarily for emission control. You can tune an ECU without a O2 sensor, and still make max power. Wideband O2 sensor is used as an air/fuel ratio gauge for easier tuning but it is not necessary for improved ignition or improved induction. It's nice to have.

No need to spend thousands on an ECU -- the extra money only gives some manufacturer hand-holding but not necessarily a "better" product. For example, 32-bit ECU is not better than 16-bit. Millions of EFI cars are using 16-bit factory ECUs including high power V8s.

MSquirts are proven and have a huge following

even an 8 bit processor can be perfect for efi its all to do with the software and implementation not to mention cpu manufacturers make 16 bit and up these days

Wow , I must eat humble pie here and apologise , I wasn't aware all the options that are available in the motec , haltec , autronic and other high end ECU' s is in a kit for the DIY's . I will have to look into that