Keep asking I want to know the anwsers as well.

Well thats debatable, the ST170 Failed to really gain from exhaust changes, the system was very good(Think I read it was designed by Cosworth Engineering)and people actually lost power when changing some exhausts and induction kits.
If you were to believe everthing then a panel filter could give you a power increase of 4/5bhp but! what I have found is that the tend to help the engine to respond better when its revved. If you place two cars together ie must ST and my mates one (dealer) the throttle response is better at also gives it a bit more of a sucking noise (Induction).If you allow an engine to breathe better it will respond better, but you can also have too much air and if this is also hot it will be detrimental to the performance!!!!!!!! As for insurance & warranty no problem with either as long as it is a O/E Panel Filter such as Pipercross of my preference K&N, hope this helps. I am checking into the exhaust at present this may or may not affect warranty, but would affect insurance. will come back on that one.

Its a much mooted point on any forum, whether panel filters or induction kits by themselves are worth it. If you're looking for a noticeable performance increase then you'll be disappointed. I had both a K&N panel and a K&N 57i (not together of course!) on my old 206 and with neither did I feel I was going any quicker. The 57i (a cone filter kit) made a lot of noise and not much else, and the panel filter gave a slightly better than standard induction noise above 4,000rpm. As Phyzzo points out, if you go for an open cone filter, you need to make sure its properly shielded from the heat in the engine bay, otherwise you'll lose bhp.

And yes, you will need to inform your insurance company about either, as they are considered to be performancing-enhancing modifications, even though they don't really enhance performance (read the small print of your policy very carefully).

Combined with more extensive tuning though, such as replacement manifolds and exhaust systems, a properly placed and shielded induction kit will add to the overall bhp increase.

I think I will stay standard for a while when mine arrives...

Not planning on doing to much to it anyway, but if the filter is just gonna change the noise slightly then I dont think the hassle with the insurance is worth it just yet

I think the ST has a decent induction noise anyway, particularly once you get up to about 5,000rpm.

Parksey, the reason that I stated "OE Spec Filter" is because you don't have to tell your insurance company. The reason for this is an OE (Original Equipment)Filter is any make to that specificatation the filtration material is irrelevant, it just has to fit in the same way into the same airbox. This is not classesd as a modification an indution kit is. Mind you I just rang Norwich Union about the proposed exhaust change and they were not bothered as long as the cat stayed.

Fair point, Phyzzo, but I think its ultimately down to the discretion of the insurer as to whether they deem it to be a performance-enhancing modification. I'm always inclined to inform my insurance company about any modifications, bearing in mind that when you take out the policy one of the things that you are required to confirm is that the car has not been modified from the manufacturer's standard spec. Like you've found though, when I had my 206, the insurers didn't charge me any extra for stuff like the K&N, replacement exhaust and lowered suspension, it was just a requirement that they were declared on the policy.

The best bet would always be to check with your insurer before you make any modifications though.