Just making sure this isnt to much of a problem. After zzp computer install I started using 91 octane and I can tell my exhaust smells a little weird. I have a friend with an alero that smells the same. Is it just running rich or lean? or maybe Its the new down pipe with the high flow cat. I dont know.

 

Most likely you are running rich because it is safer to tune a little rich on a mail-order-tune.

 

OIC. thank you Chibi

 

Easy one I'm sure but should a wideband O2 sensor be installed first, or will the tune compensate for that?

 

A wideband only tells the tuning software the mixture of air and fuel so that you can adjust accordingly.

Unless you are tuning at that current time, it doesn't need to have a wideband on the car.