lol, yeah u mean like this, listen pal...best get the 146ti lump in there sounds like a mans car, none of this sticking your top trump cards in the spokes of your wheels.
Get the twin dtm exhaust if u can afford as the first one on your list, then the air filter...the k&n kit for the 146 isn't bad comes in around th £70 mark, makes a differences to the tspark especially the sound but needs the exhaust for full benefits. The k&n kit is good in mid to high revs but dead in low revs...trying another kit soon.
The cheapest option however is to have the cat removed between MOT's...apparently lol! Will sound different and allow your car to breath a bit better.