Wondering if there's any gain in HP by installing the headers on our cars, any dyno sheets?

 

Depends on your power levels and the headers you are looking at... Wouldn't surprise me for some of the headers to actually cause a power loss. I think most people stay with stock or ported stock

 

about the only reason to not use stock headers would be v band turbos or turbos to large to fit the headers . with over 1300 hp capability with stock headers the money spent is best used elsewere

 

Dude - nobody has made 1300 with stock headers. More so, nobody has calculated the flow of them.

I agree - use stock unless your turbos / wastegates do not fit.

 

Depends on design. Pipe sizing, equal length? and what other mods do you have? If you have enlarged throttle body, improved intake system, increased Turbo boost etc. the horse power produced would be better.

Here's a word from the engineer.

 

spoolbus AND black horse turbo had oem headers. spoolbus 1050 and bht was over 1100 rwhp. add driveline loss and you practically sitting on 1300 hp. maybe not exact but dang close.

if you like ill correct it to say stock headers are good for over 1000 rwhp. is that better? since proefi has emap (exhaust manifold absolute pressure )sensors why do you think the flow hasnt been calculated?

 

But it will crack after sometime

 

I had 1500$ gmg headers and they cracked as well.

 

I agree most of aftermarket headers cracked faster than stock. Very few aftermarket holds fine

 

pretty sure that stock ported headers have been proven to gain. my speed shop installed mine well before i got this current car. but i've never a/b'd the difference since it hasn't been dyno'd be me, not have the headers been moved.

i only know they didn't port/polish whatever and install em to make the car slower.

 

I think most here are quite familiar with how headers function and what benefits they can bring. In this specific application (996/7.1 tt) though, there is next to nothing to be gained and likely much to be lost. The OEM exhaust manifolds are a very solid, double walled design and flow quite well. They can be improved by porting - there are a number of threads that address this.

The only thing that aftermarket headers generally add in this application is bling.

 

stock headers crack? yeah, i'm going to leave them alone. until I go with bigger Turbo's

 

^ generally no. Aftermarket headers generally - or often - do.

Where were you reading that stock manifolds crack?