The "myth" again.
No engine runs better with back pressure, but it is a common myth.
Tuned exhaust systems create LOWER pressure at the exhaust ports, they do this by using a smaller pipe at the exhaust port that dumps into a larger pipe(collector).
The smaller pipes size and length is what determines the RPM range where the lowest pressure and highest power occurs.
This allows headers to be designed to move the power band lower in the RPM range, or higher.
Headers don't add power, never did, but they can move the power band for your use, i.e. lower power band for quicker starts, or, higher power band for higher speed power
The size and length of the pipe at the exhaust port is important in creating the Velocity that causes the LOWER pressure, when the exhaust from one cylinder gets to the larger pipe its velocity creates a lower pressure in the other 3 pipes(4cyl), like a siphon effect, this can be tuned to create the lowest pressure at one specific RPM, that establishes the center of the power band.
The back pressure myth came from people putting on larger pipes and then losing power.
The incorrect conclusion was "engine needs back pressure", OOPS, lol.
The larger pipes at the exhaust ports INCREASED pressure, because they lost the Velocity that creates the low pressure.
Not having a Cat will not effect performance one way or the other, another myth, but if vehicle originally came with a Cat then it is a $2,500 Federal Fine for removing or not having it installed, nothing to do with State requirements, it is a Federal beef.
Will you be caught?
Not likely but not 0 either
I would see if you can ID the type of headers you have, they could be a high power band model so low-end would be less responsive.
Last edited by RonD; 09-08-2014 at 10:58 AM.