check out the japspeed site. i just bought a full system for my 4 and was very impressed with the quality for the price. (though don't think it is 3 inch as el recommends but worth a look)
Features:
* T304 mandrel bent polished stainless steel.
* Fully TIG welded.
* CNC machined flanges for strong, solid support and accurate fit.
* 3 Inch (76mm) bore with a 2 1/2 Inch (76mm) outlet.
* Increases gasflow and offers performance gains of up to 15 BHP.
* Stainless steel reinforced flexi joint to prevent cracking.
* Gaskets and bolts included.
£129 (inc vat & shipping)