You won't get any gains from a induction kit or panel filter and if you do I'd be surprised if it was over 1bhp!! I put a k&n cone on mine for the looks and sound. As for exhaust I built my own as said it comes with a 4 branch manifold and sports cat as standard so I got a focus tdci back section as it has no box in it and had a 3" tip welded on it. Wasn't much louder but did pop abit and looked a lot better and all for under £30. I'll see if I've got any pics of it.
I fitted some performance 3000 30mm lowering springs off eBay on mine and the handling was really good. It would out handle my fabia vrs I've got now that's got coilovers and uprated rarb easily. If it was me I'd spend the money on the handling side of things as this is their plus point