Iv been looking at headers for my newage and it looks like it could be a minefield. They range in price from about £250 from flat4.co.uk to over £800 for ceramic heat wrapped ones. They do apparantly need to be heat wrapped, either with incredibly expensive ceramic or with tape, which is a fraction of the price but dosnt last anywhere near as long. Standard headers, and most aftermarket ones are unequal length and this is responsible for the subaru burble, you will lose this with equal headers. Some ebay sellers claim 30bhp, which I think is totally optimistic. If you are up for a journey scoobyclinic do header and up pipe fitted for £500+vat. If you can fit them yourself great, otherwise its a lengthy job with lots of labour charges, figure 4 hours plus.