Quote:
Originally Posted by Arxangel
See, it wasn't so difficult. This is the answer I was looking for in the first place. I am sorry I asked my question in the wrong way and misled you.
As for the comparison, in this case it does not matter if the engine is NA or FI, I am talking about the fact of having a Performance Kit from BMW. They could do such a kit for any model they like. I was merely saying that I wish they had produced one for the Z4.
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There's not one because there's not a reason for one. Naturally aspirated vs. forced induction. When air is compressed, it gets hotter. All of the heat that was in a large volume is now in a small volume.
Forced induction engines run hotter by nature- turbos get red hot, air is compressed to a greater degree, etc. Aftermarket tunes increase the boost pressure and add more heat. This isn't the case on a naturally aspirated engine. There is a big difference in naturally aspirated and forced induction tunes.
Tire sizes - go to tirerack.com and read up on what the measurements mean. The difference between 225/40/18 and 225/35/18 is the amount of sidewall (and therefore the diameter). The wheel size is still 18".