just completed my header install and the car is actually quieter than it was with the manifolds! is this normal? I have a flow master cat back with an 80series and off road pipe and I was just wondering if any one else has noticed the same thing?

 

Stock manifolds produce a lower dB sound than headers. Headers are louder than manifold though not as much low rumble

 

get a cutout

 

headers will tend to even out the exhaust pulses so you don't get a lot of sound wave collision like you would with stock manifolds. It sounds quieter but IMO it sounds more refined.

 

Even though it may seem counterintuative, improved combustion effeciency (which is what headers do) will result in less energy being wasted as noise. If you doubt this go find yourself the nearest hi-po wankel engine, which burns a ton of gasoline in the exhaust Proper cam timing with full length headers will be more mellow than the noisy truck sound of a cam too large for the heads, dumping from restrictive exhaust manifolds into a large pipe and cutout. The pitch/tone is also changed which may make the percieved volume different. Of course, no matter what a healthy SBC is going to make some noise