3406E Exhaust manifold

I have a 3406 E , originally factory was 475hp and with the bigger injectors it could be turned up to 550hp with the original software. I have reflashed with C-15 software aftermarket and the shop said it was about 600hp, whether that is to the ground or at the flywheel, i couldnt say.
the pyrometer runs a little hot I think, if i am pulling a hill with any kind of weight on i end up down shifting to keep the temp below 1000.. I like to stay at 900 or below.
So i am looking at a turbo and probably exhaust manifold. The turbo i think would do the job is either BW s430sx,- 78 mm. debating on 1.32 ar which rates at 650 hp, or the 1.45 ar that rates up to 750 hp. I have heard the 1.45 gives a little power at the top,, but the 1.32 will spool a little faster. most of what i do is highway, not that much stop and start so spool speed isnt that big of a deal. any experience with either ar and how it performed?
My main question is this. The exhaust manifold. It seems there are a few hi-flo on the market, the bully dog, pdi, for around $1500. i see aftermarket oem manifolds for around $350.. IF i got one of the aftermarket oem manifolds,, and had it ported and polished, ceramic coated,, would it be performing as good as the PDI or Bully dog? Or are the more expensive manifolds actually redesigned to give better flow? I called a place that does that,, So Cal porting and polishing, and ask for a ball park number,, he said about $375 to port, polish, and coat it. Now my investigation is still preliminary, and i just want to know any thoughts by someone who does work on them.. and sees the change in performance when swapping into the high flow manifolds..
There is also a stainless manifold ive seen on amazon and ebay, claim to be hi-flow, and to get the same increase in hp and mpg as the PDI and bullydog, there price is about $950 for those.. but they seem to be coming out of china and there is no manufacturer information. i would like to avoid mad in china if i can.
So any helpful advice on upgrading turbo and manifold.. My turbo is stock and still performs but the waist gate has waisted away and is wired shut, and is begging to be replaced..

 

i had it flashed by a guy south of new stanton pa. i can give you his name. there is quite a few guys around who do it. another guy i know is north of Altoona, pa.