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      01-25-2013, 12:18 PM   #46
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Drives: G01 X3 M40i
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2008 BMW 328xi  [4.10]
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Originally Posted by Modded328FTW View Post
No offense to the OP, but this is just 1 review. There are a few threads that post actual data about whether the tune shows gains or not.

Hard to say how much the car has gained without dyno numbers. I personally am not a fan about the "butt dyno" threads (good/bad).
Originally Posted by Propagator View Post
As OP pointed out, I don't think he was trying to prove that there is no power gain at all. Rather, I think it's about setting a realistic expectation on what it feels like to have a few extra ponies.

What is the typical gain that you expect from the AA tune? According to AA, it s about ~15HP, and 12TQ right? Taking that at face value, that's about ~5% improvement over the stock level. In terms of power to weight, then, it is roughly equivalent to losing ~150lbs of chassis weight (obviously only regarding straight line acceleration). And that's the difference between having a medium size passenger and not having one.

Does that make a difference in how the car feels? Sure, especially just after you pick up or drop off somebody. But after driving around for a while, that difference would become more difficult to feel through your butt dyno. And does dropping off your buddy suddenly makes your car accelerate so quickly that it "pushes your back in the seat"? Well, of course not. The car will feel a bit more lively, acceleration a bit more brisk, but 10 minutes later you'll get used to it and won't even notice the difference much.

And that's using AA advertised numbers. No disrespect to AA, but as a rule of thumb I am always a bit skeptical about vendor published numbers, as would most people here. We already know the outputs vary quite a bit from the factory, and while it's comforting to think that MINE would be on the higher end of the spectrum, I think it's unlikely that any vendor would advertise the worst case scenario, so it's quite likely that your gain may be somewhat less than these numbers.

So all things considered, I would not expect a "back pushing" level of change with this tune.
Exactly, and thank you for this explanation -- it really clarifies what 15 HP/12 TQ does for your car. Well said!