Just looking at air filters on Ebay.

Factory OEM replacement is around £15 and K&N panel replacement is about £40.

The 1.2 TSI has a cone filter and the cold air feed is through the top of the engine, close to the bonnet.

K&N also produces an after market system (57i), which replaces the standard air box and air filter (looks remarkably similar to the factory air box) and also changes the cold air feed from close to the bonnet to near the front wheels.

This cost around £140 and frankly I am not going to spend that much. Just want to know what the merit is of this system, it is very similar to the panel filter + OEM air box arrangement, but with a potential detrimental effect in small floods?

IIRC the 57i kit will provide better performance, buy giving a better cold air feed. The K&N panel filter will allow more air through than the standard filter.

Thanks, the difference between replacement panel filter (which is also circular) and the 57i is the cold air feed, one goes under the car (57i) and the factory version is just below the bonnet.

sounds about right, unless you are looking for the grunt i would stick with a K&N replacement filter instead of the 57i.

The replacement filter arrived today, fitted it, makes no difference in sound or performance at all, however at 33 quid, it is the price of 2 OEM paper filters so that's not bad at all.

Just realised I have been talking about the 57i above which is the open filter, the one I was actually talking about is the 57s. For those who are considering the 57s, save 100 quid and buy the replacement, it is still a cone and with very minimal modification to the air box, it would be better than the 57s.

Whilst fitting it, I discovered that the airbox is not very restrictive, the pipe work are very straight and is the shortest from the turbo and MAF on the Yeti (different from the Fabia). It would be hard to improve the design on this front.

After about 200 miles, I thought I would report back - no particular gain in performance, however there is definitely gain in the mpg department.

I could easily average high 50s on average speed zones, previously only been able to manage low to mid 50s. In town averaging 30 mph, it can happily get 60s, whereas only mid 50s previously.