I'd be suprised if the Mugen header, with other mods mentioned, garnered 240bhp.
Tony: Fair; I'd rather the power, the grand saving, and even the hassle, before shelling out £2.2k for a header, which is realistically compromised where power is concerned - You're right though, it'll get you through an MOT; I appreciate why this will appeal to people.
If the OP is serious re: catted headers - FEEL's also do one. Catted headers cost more than de-cat headers. Expect to pay £2k upwards new; they aren't the sort of thing that come up used regularly.
Piper do a sport-cat manifold; I'm not sure on the price or performance figures. They're sure to be a lot more reasonable than the Japanese offerings.