Generally, anything over 1/2 a bar should see 12.0 to 11.5 AFR. That's a nice safe zone. At zero psi, your fuel map can be around 13.0-13.5 AFR, with 14.5-15.0 happening under 1/2 bar vacuum. That's fuel, which is easy.

Timing is the secret sauce. Go google MBT, mean best torque.

As far as tools, I use my own design (RS Enthalpy ROM board) hardware with ROM Editor and a custom address file. Kind of cumbersome to tweak the tune, but I've got a good handle on what's going on. A bad dyno session might see 3 rewrites.

I had a CalumSult RT board in my car for a while. It's just a fancy ROM board in a stock ECU that does live updates. This is similar to Blackzenki's Nistune board. Again, I've got a good handle on what's going on, so I just used it for tinkering with new addresses and rarely used / unknown (until now) settings. It was sweet for that. Once I got a setting figured out, it just went onto a standard ROM board.

I also had a Haltech E8 for a while. That was a pretty standard mid-range standalone. The maps are basic, the features are overkill, and the terminology is Industry. You need to know what you're doing, how things work, and how the software/firmware will interpret the setting before you can have a perfect tune. At the end of the day, I swapped to a ROM tune with the same settings, made the same power, but was 1000x more driveable around town.

I've seen many AEMs in use and they're pretty cool. Slick user interface. At the time I was turned off by the CAS reading problem, but they seem to have that handled. AEM2 is in testing right now as well.

I once repaired a Megasquirt2. Holy crap. That was like Fred Flintstone's standalone. Radio Shack nightmare. I design high end electronics in my real job, and have a BSEE. I've seen better implementations in Senior Design Lab... which by definition is full of un-degreed people and only 15 weeks long. Megasquirt3 is actually less powerful than the new Lego Mindstorms.

No opinion on the Autronic SM8 that people have been using. Microtech has a common standalone. Or just plop 'em out and get a Motec, which starts at about $2k for a 4cyl sequential box. The M880 that you see everyone using is over $5k. plus accesories.