Contour Enthusiasts Group Archives Forums Modifications Duratec Maintenance info on gutting the precats

I don't think anyone can post an "average gain" because there hasn't been enough accurate data posted to make any averages!

Everytime someone guts the pre-cats there is something else done simultaneously.
If your pre-cats are starting to plug up you will gain back the lost power. If your pre-cats are not plugged up then I don't think you will gain any 5-8 HP. If the pre-cats have enough flow area to equal the flow area of the piping following them, then you will gain nothing other than an expansion chamber which = BAD. The honeycomb will induce some drag, but at least the flow is laminar and not turbulent which could be worth a lot of power.

What I can say for sure is I didn't notice any improvement going to gutted pre-cats, but I noticed a huge improvement going from gutted pre-cats to MSDS headers, and I dyno'd this proof to the tune of 7-11 ft-lb increase in torque in the 3000 rpm range and at least a 4 ft-lb increase in torque 2000-5500 rpm range.
They are not equivalent mods, the MSDS headers flow better, increase scavenging and are probably 40% lighter so you drop weight off the car.

I would only gut the pre-cats when they are beginning to fail.
I'm only speaking from experience since I've done both of the mods we're talking about.

warmonger