n2n2o
CEG'er
As the title says what is the mystery mod. thanks guys Chad
Gutting the precats.
Its kind of fun to see "mystery mod" again...
Memories...
hollowing out precats is... not effective unless they're deteriorated. Hollowing out deteriorated precats will restore near to factory power at the cost of some increased noise. The difference between "not driveable" and "driveable" is a HUGE improvement.
Hollowing out working precats? Some say it costs power over the whole band, some say it gains power at high RPM. That should be enough to tell you something about how useful it is.
I believe those that reccomend it as a "great first mod" actually started with deteriorated precats.
I understand that the headers exhaust pipes are seperated and they have a somewhat type of pulse setting in the tubes to have better hp/tq numbers.
So to ask you, do you think it's only the tube design that adds power? or the removal of the cat material??
More to do with the design of the headers. Even if you took a stock manifold, cut it open smoothed everything out and welded it back together you would still not get the gains of a set of headers. The stock precats are not the big gain from installing headers, it's the much better design that promotes scavenging and also flows much better.
I agree with that statement, i just didn't bother explaining myself more. I disagree with the idea that removing the precats offers no gains.
Then don't you have to use MIL eliminators? and where do you get them?