I am thinking about buying a set of those turbo manifolds sold by SS autochrome. I have heard they dont sell great quality stuff, that the metal is too thin. the metal thickness is 2.1MM, too thin?

Or i was thinking about simply buying a set of block hugger headers, flipping them upside down (cut off flange flip re-weld) the replace the stock 3-bolt flange with the T3 flange... Whatcha think?
So they would basicaly sit like this guys: https://www.thirdgen.org/forums/po...ght=twin+turbo (another Twin Turbo..Firebird..up and running)

EDIT: after looking at the headers, could i just flip them over without welding at all?
not the exact ones i would go with but...
http://cgi.ebay.com/ebaymotors/CHEVY...62583172QQrdZ1

 

Extensive modification is required to block hugger headers to use them upside down. I did it on my first twin turbo set up. You can't just turn em over, they hit the valve cover and rocker arms, and still won't bolt up. You have to cut every runner off and reweld it to the head flange at the correct angle. I think the corvette headers (that at least two other guys here run) do not require as much modification. Instead of using block huggers... it would be easier to buy a bunch of U bends and some flanges and weld those together.

The headers in your first link are also SS autochrome

 

hhmm... i was going to use the SSAC, but not sure what the thickness should be, like i said the thickness of their headers is 2.1mm. How thick are most headers?

this is what i was going to go with: http://cgi.ebay.com/ebaymotors/SBC-T...68682841QQrdZ1

 

The SSAC is 2.1mm in that AD. Read another Ebay AD and it will say 2.9mm. Who really knows, none of the knock-off ebay turbo people will post correct consistent data. FWIW, I sent in some questions to one of those ebay sellers about a turbo they sold. I ask about where to get rebuild kits, what the turbo ball-bearings were made out of, and some other stuff. It has been 3 weeks and still no response.

Anyway, a typical N/A header is 16 gauge (1.25mm) or 18 gauge (1.59mm) mild steel. I made my manifolds out of stock TPI units (89JYTurbo knock-offs). The wall was about 3mm to 5mm. I bought some mild steel weld elbows from McMaster Carr for some new custom manifolds. The wall is .140" (3.56mm). I am making the head flanges out of 3/8" mild steel. It should be strong but heavy. I don't mind losing speed for reliability.