I settled on the tomei UEL, check out the website. Catless exhaust on bone stock engine with 8 lbs of boost did 255whp and 275 torque. This was all at 5k rpm we didn't even take it any higher as something didn't sound right (turned out the oil pump was failing) Tuner was impressed with the headers, said typically my car would do 230-ish.
There is only one set of tomei for single scroll and they are light weight but build quality is top notch. UP is included along with heat wrap for the whole setup.
If you are after noise though even the UEL are on the reserved side unless you get on it, or course I have an STI catback on it.
BUT IMO, P & P the existing manifolds and a GS cross pipe and ceramic coat the whole thing is not going to touch the Tomei setup. If you look at the manifolds (I can take pictures of them if you want) they just aren't made for speedy air flow.