I read that Borla headers will loose HP, and are the worst out there.
I am just curious what is wrong with them. Aren't all headers just the same bent pipes anyway and Borla seems pretty reputable brand...

 

Do you have a reference with before and after dyno charts? Thanks.

 

Frankly, I read that after I have purchased them...
I am just curious of the science behind this. Is it too narrow tubes , wrong angles or something else?

 

I remember Mr Borla saying that they just released their own headers because people wanted them. But I suspect it was a half-asz attempt with very little R&D. I'm curious why they perform so poorly as well. My guess would be poorly designed bends and/or small diameter tubing. I dunno tho.

 

Maybe they perform poorly without tuning. Otherwise I don't know.

 

I believe the one of the flaws is that the tubes are unequal in length.

 

unequal or equal are not inherent flaws or benefits...just differences

what is wrong with the Borlas is they simply don't provide any benefit. Lots of their products are great - the headers are not one of them

as for the reasons, I doubt anyone has sat down to figure that out, since there are so many other units out there that work great out of the box, that the 'why' reason is largely inconsequential

 

But isn't it hard for a true tubular header to work worse than the stock cast iron exhaust manifold which has very small inner diameter and sharp bends?

Edit: or provides no performance gain over the stock cast manifold

 

the stock manifold is really not that bad of a design....hence why headers on this car typically do not add nearly as much as they do on other cars

 

Actually, Borla at least pretends to be equal lenght, i.e. subjectively all three look close enough. Tubes do look kinda thin, though.
On a side note - stock headers are not cast, they are two stamped steel pieces welded together.

 

Thanks for the info on the stock manifold; but may I ask if there is any performance or reliability difference between a two pieces steel stamped manifold and a one piece cast iron manifold?

Thanks