Agreed. If this is the case you're good to go. But if the header ports are smaller than the head/gasket you have a problem.

 

Sure, not leaving a certain lip at the top of the header results in harmonic distortion. These harmonic waves will travel back through the valve train and result in a slight loss of power.

This isn't new in exhaust science.

 

Acts like an anti reversion cone in the exhaust pipe flange

 

Interesting. Have any sources? I've been reading about backpressure and scavenging but haven't found any articles about lips in the header affecting harmonics. Thanks

 

I believe one source is A. Graham Bell's book, Forced Induction and Tuning

 

Variable cam timing motors are not as critical on that issue as normal cam timed motors and even then it usually at trade off in power in certain RPM levels ,,lose some low end gain some high..
All the tech stuff I saw and read in my years > a lot of old info doesn't address newer technology like variable timing,,D Ports,etc.

 

Stock headers, if memory serves, are good for 600 to the wheels.

I'd put the stock headers back on and use that header money for new turbos.

 

contact me if you need to get new headers or gaskets sourced

undercoverperformanceinc@gmail.com
lawerence