A lot depends on budget/spec.
Under 400 BHP go for Harvey ported headers with a matched up-pipe for your turbo Jaffa also does a good job of porting headers (not sure if he ports the collectors though) but does not do the Up-Pipes (as far as I know).
Over 400 then look at the 3 bolt headers (GT Spec) either from RCM, Lateral or Advanced Automotives Harvey can also supply these with a custom matched Up-Pipe which will iprove both spool and torque over the std Up-Pipe (also at a good proce and DEI heat wrapped).
One other option which I keep toying with is a set of 2 bolt up-pipe tubular headers from Williams Motorsport (Andy built my engine) purely because they are so much cheaper (Around £200)
eBay Link
I know the 2 bolt up-pipe can cause issues but you could almost buy 3 sets for one set of RCM/Lateral!
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2005 Spec B 6MT - KiDO tuned (~270Bhp)
Custom exhaust - Cosworth filter - Samco Intake - Tints - Bilstein B8/B6 & STI springs - SuperPro ALK - Whiteline positive shift kit, rack mounts, rear adjustable camber bushes, front ARB mounts & strut brace, 20mm rear ARB with AVO mounts, - Hardrace Gearbox and pitch mounts - Prodrive PFF7's - Front Brembos - Kenwood CarPlay - 1/2 carbon grille - STI front splitter