E30 FBO map ok for stock car w/E50?

Could the Cobb E30 map be used with an unmodified stock car and E50? I saw the logs, and there were no ignition corrections in those few logs that I saw. I believe the fuel scalar should be adjusted up though to be on the safe side not maxing the trims. I told him to pick the scalar from the Cobb scalar table.

Anything else that would need to be taken into account and should be adjusted in the map? For example, anything related to keeping the stock cats alive? I guess the Cobb E30 map would be the best starting point for him running stock car w/ E50 and make minor adjustments to it if needed?

Sounds good to me if the logs are clean. Adjust the scalar, and assuming the fuel pressure is holding you could richen the afr targets slightly and flatten the iat timing reduction tables a bit to give more consistent performance. As long as trims are good, fuel pressure is good, ignition advance isn't being pulled by the handful and there are no timing drops it's safe.

I'd be concerned about back pressure on the turbos, can't remember if there's anyway to measure it with the AP but try to monitor EGTs

V8Bait is right although it's probably not ideal as the heat on the turbos will be increased with the backpressure on the stock hardware.

The ethanol content will help to alleviate some of the backpressure from the primary cats. Another thing to consider is the E30 map is designed for an engine that breathes better so boost control may be less than ideal(there are also a couple tables that affect MAF calcs that are changed and that can lead to boost control issues on a stock car.) Keep an eye on req vs act boost and TPS drop outs.

More than likely bost control will be a little off target for sure, most likely under target up high since there won't be enough wgdc there to hit the right pressure ratios. Anyway, while the turbos will likely see more heat they at least won't have to spin as fast to make boost, I'd wager turbo life will be more or less the same with vs without cats (more heat vs higher shaft speed), but the turbo guys like Tony @VargasTurboTech would probably know what kills turbos faster.

Engine wise the E85 should keep things safe, but 18psi on a stock car is mush less airflow than 18psi on a FBO car and thus not as much power. Safety wise shouldn't be a problem though. Motor is pretty stout. Just do us a favor and don't throw 15.5 degrees advance flat across the Rev range at it pl0x.