Hey all. Have a set of GT Spec V.II headers for my '04 STi. Noticed that the head to header flanges are not perfectly level. Specifically, the middle is maybe 0.5 mm higher (the area between the exhaust ports) than the outside of the flange. This is on both header to head flanges. My question is: what is the best way to smooth this down and make it perfectly level? I have a fairly complete set of tools, but no way to ensure that I'm actually making the surface completely flat and parallel to the heads.

I guess I'm asking what type of tool/machine should be used? Anyone had this problem? I already have new 5-layer steel manifold gaskets and was anticipating using the copper silicon sealant, but I'd rather have a perfectly level surface to start with. They are used and are therefore out of warranty. Any tips would be appreciated.

Bryan

Cut the flanges and off and weld new ones on.

thats a bit extreme but ...I guess as a last result that's what will have to be done.I'd run the flanges across a stationary belt sander then use a large flat file and file the rest down.

just my .02

Take it to the machine shop, they can deck it.

Bang the flanges with a hammer on a welding table and then just sand them a tad on a belt sander or take to machine shop to lap.

Take it to the machine shop, they can deck it.

^^^^^^

Do it right the first time.

Do you have leaks?

On the other hand why worry and sweat it out. Put the stock headers back on and you will be on your way.

Cheers

Nick

Why are they made like this to begin with?

Why are they made like this to begin with?

The heat from welding distorts the metal.

I figured a machine shop would probably be the most effective route, but I just wanted some feedback as to whether this could be done at home with common tools. FYI, yes they do have a leak at both flanges. I know the stocker is supposed to be fairly effective (especially with a proper port match), but I couldn't pass up the deal I got on the header set. As I said, the distortion isn't more than 0.5mm (probably less) on the flanges, and I'm sure the 5 layer gaskets and copper silicon sealant combo would seal everything up. Just want everything perfect, you know?

Anyone have an idea as to pricing estimates on decking the flanges (just a ballpark figure)?

maybe $40-60 at most.

I know the stocker is supposed to be fairly effective (especially with a proper port match), but I couldn't pass up the deal I got on the header set.

That was somewhat true on a mildly modified 2.0 WRX. After the great header debate was finally over, a TXS Stage IV WRX gained 20whp running a header - and that was before re-tuning.