They don't come with a 'performance' sticker.
cars already mapped,just thought id put k&n in as you can clean and re-oil so no need to buy filters again
In terms of noticing a difference in engine power, something else of interest is that human response feedback mechanisms are logarithmic. Hold a one kilo and a ten kilo mass each in different hands and you can obviously tell the difference. One and two kilo you can tell the difference. One kilo and 1.5 kilo and you can just tell the difference... as the differences between two things that you're comparing reduce down, your ability to perceive those differences reduces in sensitivity at a rate that very closely approximates a log curve.
So 150:152bhp, you would not be able to discern any difference at all. 150:160 you might, might just notice it, assuming that no-one had told you that there was a difference. The key here is that if you've been told about it, you'll go looking for it. And what is amusing is we find that people will swear down blindly that car XX is noticeably faster/ better performing etc than car YY even though there are no differences at all to them (except for the driver comparing them being told beforehand that XX has been uprated, tuned etc).
The placebo effect is responsible for a lot more in one's perceptions of how things perform/ handle than you might think!!!
The rule of thumb I found was 10%. Very few drivers will detect a 10% increase in power. Interestingly we are more attuned to when things get worse as almost all drivers will detect a 10% drop in power.
No one does