if a car is tuned what is purpose of having the wideband guage, will the AFR change after u tune it, my understanding is that u need to monitor AFR all the time when racing/ changing set ups

I am running a LS right now would it be a good investment?

 

If the tuner is very good then there is no reason to have an Air/Fuel gauge per say. The issue comes in when problems arise or your tune isn't very good to begin with. It all depends on what kind of fail safes are in place to help prevent catastrophic failure from loss of oil pressure, fuel pressure, over boosting, leaning out, etc...

Bottom line -

Is it a must have? No.

Is it good to have? Yes, extra monitoring devices can never hurt keep an eye on the health of your vehicle.