I fitted a cone filter (with a cold air feed) to my last car hoping to improve the performance and make a nicer noise. However, there was no noticable increase in performance and the noise was more of a rasp rather than the growl I was after. I you want more of a low end growling noise then I guess the only way is an exhaust change?
If you are after a little more performance then you might be better off with a non-standard filter in the original box for less restrictive air flow. A K&N panel filter to fit the miggy's box would mean you can keep the box in place and use the existing cold air feed.
Also if you fit and induction kit then ideallyyou need to tell your insurance company that you have modified your vehicle. If the worst does happen and you have to claim then it's possible they'll use it as an excuse to not have to pay out. I told mine I had a 'non-standard air filter' and they said that was fine and didn't charge me more, but at least I was safe in the knowledge they knew and they couldn't use it as a 'wriggling out clause'. (Technical insuance jargon

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Hope this helps and feel free to correct anything peeps!