Originally Posted by Speedy

Your wide band needs to be installed BEFORE the cat to give the most accurate reading. Usually they're placed close to the stock sensor.

An AFR of 10 is definitely rich, but adjustments in AFR don't add GOBS of power. You'll pick up some, but not tons. On a stock motor I'd want the AFR around 11.2 -11.5 in this car. That's a nice safe zone to be in for FI to keep things cooler in the combustion chamber.

TIMING is where you'll make up your power. On the Challenger for EVERY DEGREE of timing we add we get "about" 20RWHP.

Stock, I'm told the Z runs around 20-22 degrees of timing at WOT. However on FI, you have to back that off to avoid detonation. I'm curious where your timing is right now with the STS stock tune. Can you find that out for me?

On the Challenger several factors affect the final timing the engine gets, like intake air temp, knock sensors, etc. My Challenger motor is a forged balance and blue printed engine at lower compression (9:1) for boost with special ring gaps etc. I run 93 octane in it and on that 93 octane tune we start off with about 18 degrees of timing at IATs under 100F. At 115 the timing drops to 16 degrees. At 125 it drops to 14 degrees and pretty much stays there. I run about 13-14psi of boost on that car, and my IATs are about 90° over ambient at the end of the 1/4 mile or a hard full out pull on the highway. So if it's 60 out, the IAT gets up to about 150.

Not sure how that'll work out on the Z, just giving you my stats as an example to go by so you have SOME idea. Turbos are more efficient than the roots blower I have on the Challenger, so your IATs should be lower.

Lemme know on how much timing that tune has today.