wideband is now so inexpensive these days, you could get them. Try AEM UEGO.

they're fairely simple to install with the plug and play wiring harness with bosch plugs.

They'll give you the a/f ratio in sweeping led and digital layout (for turbo cars that goes under 11).

EGT is great, because you could monitor the temperature of your engine. They give you the right away info on what's going on in your engine. If it goes colder you'll know it's lean, if it's running hotter, you know it's rich... and few other thing, like if your EGT temp goes up, you might have blown an engine... etc.

anyway with both the EGT and A/F you could monitor and tune your car accordingly.

Since you could have the perfect a/f ratio and still have things go bad inside your engine, I think it's good to have EGT to monitor what you're doing is right inside the engine.

my 2 cents