No one here can tell you if it's safe or unsafe.

Peak power is generally considered to be around 12.5, but with all things there's variation.

It's not as simple as lean = unsafe and rich = safe.

If you're lucky Ratter or one of the other guys with tuning knowledge will pop in and be able to explain it better.

I'm pretty sure my car ran 11.5 afrs on e85, which I thought was quite low.

that's erring on the very safe side especially on e85, can afford to lean on it a little harder, definatly see more power on e85 when leaned out a touch compared to what you'd see on 98. 12.5 is a pretty happy place & before you say it JET yes its done in lambda but you can convert that for them if you like

Is there a huge difference between 12.5 and 12.8? Is that the difference between the car popping or not?

I do not understand why they would push the car that hard, you have all the supporting mods, why not have some safety in the tune , you will lose around 10 rwkw, but it will help your motor in the long run.

are ya sure ya heard them right, got a dyno chart with afr's on it, that's a pretty amatuer misktake to do that intentionally???

Adam is correct, a car can be run at 13.5:1or leaner if the spark table is set up for it, although combustion temps, (not coolant temp) will get higher with a lean mixture.

To those quoting AFR's on other fuel bseide unleaded, are you sure the dyno was set up to read the other fuels stoich value???? bet you don't know for sure, if you talk lambda we know things are reading correctly

12.0 AFR safe mate. I like mine about 11.8 on pump fuel. who tune the car mate.??

11.5-11.9 is good for pump, 12-12.5 can be ok depending on how much timing you have

Exactly ratter!! So many people forget this still!!