For the rest of us - lets be honest - what real world difference will you see with a claimed 5 bhp (just an example!) increase during your daily commute.
As such, and with far easier ways to improve the power, you just need to look at your reasons to own or not own one, and decide for yourself.
I went for the 'middle ground' of a K&N filter inside the trash can, as I'm not too bothered about the chavvy noise, or the slight (possible) reduction in filtration, or anything else - but it suits me to have a unit that i wont have to replace!
As for the theory of hot air being less powerful than cold air - YES, IT IS - FACT!
I could explain the science, but very few would understand it, and if you did, then you know it already
In laymans terms there are less molecules of oxygen (and every other gas in 'Air') in a less-dense charge to the engine - the turbo will (by definition) compress the air, which has a double-edged sword effect - compressing it gets more Oxygen into the engine, but also increases the heat in the gas (simple physics - remember Charles, Boyle, Henry and all them other clever blokes who decided these things!), which means that it will be less dense than it could be.
With it so far
We have a charge cooler to bring the temp down a bit after compression, which should put it back to ambient (ish)....
...however, by increasing the boost pressure, you increase the temp increase, decrease the time the 'hot' air stays in the chargecooler, and therefore the final temp is going to be higher
Whether there is more free O2 in a hot mix under more pressure, or a cool mix under less pressure is another arguement - suffice to say that nothing is linear with the calculations, air pressure and air quality all make a difference - and you will develop more power driving through a leafy forrest than you will in a smoggy city - but I bet you can't tell the difference!
Bottom line - if you want one, get one (it's your car) - but don't ask me to convince you one way or the other


