I don't think there's enough "slop" in the factory "tune" as a whole to gain much at all really with stock and bolt-on parts. Even if it was datalogged I bet the bulk of the "tuning" would be timing advance. "
As for the slop, I'm not talking about the tune, I'm talking about the cams/valvetrain. See below.
The factory tune is the factory tune/strategy. Similarly, a vendor's (like bama which gets the bulk of the bashing from what I've seen) "box" or "canned" tune is that tune/strategy. Identical between cars and handhelds.
BOTH are written to be safe under all fuel/atmospheric conditions with the stock tune overly concerned with nvh and emissions, where (one would hope) the vendor tune is optimized for performance with only passing reference to the emissions parameters (and maybe with some of them literally turned off to make that happen).
I know most everyone posting in this thread knows all this, but people reading don't always.
And we DO have to remember we're talking about double or single-digit differences. At the low end likely within the range-of-error for a dyno anyway. That said:
What I was saying was that depending on whether the strategy/tune had been modified for the particular vehicle (either on a dyno or datalogging) its near impossible to guess or predict:
1) what the ultimately peak (number) gain is/was; and
2) what the tune did to the drivability/power/performance (typically measured by repeatable/averaged 60foot, 1/8m, 1/4m, and trap speed -- for road race guys its certain sector times and the mph at certain spots on track that are differentiated for the most part solely on engine power).
The difference between a canned/box tune and one customized for the vehicle (even with just bolt-ons) CAN - not always, but CAN - be night and day. Noticeable by ANYONES butt-meter and patently obvious on a time slip. It should ALWAYS be measurably better unless the tuner is a hack.
The primary reason for this is that even a canned performance tune is generic and conservative. Less so than the stock tune, but a proper tuner can do two things: 1) push the boundry/edge knowing more about the vehicle/situation; 2) identify how FAR they can push the tune given those parameters; and 3) identify whether modifications to the spark and fuel table that might be counterintuitive might work on that particular vehicle and produce a fatter powerband. A good tuner isn't JUST tuning to give you a big peak number - what he's doing is taking (typically) HIS baseline tune and tweaking it given the unique motor.
As for my valvetrain "slop" comments . . . you can have cams in these motors that can be more than a degree advanced or retarded (installed without intention or knowledge of this change). AND WORSE this can be different from side to side, so you can have one bank advanced a degree and one bank retarded a degree (or more maybe). Both cams advanced or retarded has an effect on the powerband - a DEMONSTRABLE, OBVIOUS (predictable) effect that you can see when graphed and feel from one identical mustang to the next. Even more interesting, through tuning, I can take advantage of this cam phasing change (whether its more tq or more hp depending on advanced or retarded) AND both maximize AND do a little compensation BC the "edges" are moved from where they would be if everything was straight up.
This, in my view, explains why you have two guys with identical cars and identical mods who buy that same boxed tune and one guy can prove it helped with dyno graphs and time slips and one guy says it sucks and can prove it with dyno graphs and time slips after switching back.
I know I'm shilling for custom tuning (whether on the dyno or remote datalogged) but I'm not in the business, just saying.
I think JonR might be on the money. He's in the ballpark at least.
I agree. I just thought I'd give the op a little pleasant thought: if it was customized JonR could be low, and if his car happened to be a factory freak (in other words either equally advanced or retarded), similarly, even the box tune could have made a bigger improvement and it might be faster off the line, or better in the top-end charge, than stock.
Of course, he could have out of phase cams, and a factory freak gt with a stock tune might walk him . . . along with the euro sedan in the next lane
Hey, not meaning to start an argument on Christmas btw. Happy Holidays everyone!