One day i must get around to PM'ing a moderator to create a sticky thread on air filters...
OK, aiculedtzu, you're bang on. You've gone through the learning experience and found out the hard way the pitfall of a cone filter.
To make it explicitly clear, open cone filter kits were originally conceived many years ago when engine bays were far roomier and underbonnet temperatures were far lower. Now, they are suitable, really, only for the audio effect. i.e. boy racers who want lots of induction roar. If you are after a performance improvement, the filter MUST be isolated from the engine bay. aiculedtzu did this by carefully siting his filter and routing cold air to the filter location. In effect, this was now functioning as a CDA.
Before i go any further i must say that a CDA is simply a cone filter - usually with a reverse cone at the tapered end - fitten inside a cylinder.
So, you may ask, how does that differ from a standard airbox? Well, it doesn't... All you're paying for is a good filter element and the ability to position the housing. For a 147 or 156 TS in standard or moderately modded form, it's perfectly adequate to fit a good filter in the standard airbox and simply replace the inlet pipe with one of suitable diameter - eg 3 to 4".
Briefly, while i'm on the topic, there is absolutely nothing wrong with oiled cotton filters. The scarmongering rumors regarding MAF's dying was commercially based and not technically correct. The MAF's were damaged by oil originating from the engine breather vent, being fed into the inlet after
the filter unit. Engine oil vapor was coating the MAF, not oil from the filter... So, a word of warning there to anyone with an aftermarket filter fitted. The crankcase breather should be installed with it's own filter, and feeding into the inlet before
the main air filter element...
OK, back on to the original question...
If you have a 2.0TS outputting 200bhp (i reckon there's another 30-40 to be had there) then i'd recommend fitting something like a BMC CDA. Keep the filter housing as far away from the MAF as possible, otherwise you'll be getting rough air passing over the element which can result in inconsistent outputs.
Direct the feed pipe to the front area of the car. Do not have the pipe inlet facing directly forwards at the front of the car as the velocity miss-match will be restrictive. Try behind the bumper, perhaps with some air directed from the front.
P.S. What throttle body do you have fitted?
P.P.S. Dupes, thanks for the kind words