Skull Crusher

Carbon deposits. You can't tell from your exhaust tips if it's to lean. Carbon is the black residue left over from the burnt fuel. With 10-15% ethanol used in most fuel today, it leaves a black carbon residue which is collected at the exhaust tip or exit. Every automobile today will have this residue.

You need to run a spark plug chop test and actually look at the base of the spark plug insulator with a magnifying glass. If it's really dark brown or black you're running rich. If it's really light tan, light gray or chalky white you're lean. What you're looking for is; a medium to dark tan. You can install a A/F Gauge but it's readings are more relative to the climatic conditions.

If your running an intake, headers, test pipes or HFC's, cat back and improved intake manifold you might be a tad lean, possibly. If not, there's no way the ECU will allow a lean condition.

Another way to tell is to pick a specific gear 2nd-4th, hold a specific RPM at around 3700-4000 and see if the Z surges slightly. You'll know exactly what I mean if you feel it. If it does, then it could be an indicator of running lean. You will also develop a lean "POP" under deceleration in every gear but will be progressively louder under higher rpm load in lower gears.