You might have 2, Ive read that mid-model year they switched to 2, My 05 has only 2, Im thinking it depends on when you truck was made early model year or late.

 

it depends on where you live on how many cats you have. i live in California and they way they are here im surprised that i dont have like 8 of them.

 

Exzactly, my 05 only has two

 

Some rear cats feed off of an 02 sensor. And for sure, this will kitty litter your dash with that poo sea signal CEL (check engine light).

The pipes are huge so it is like a normal diameter pipe without a cat in it. The flow it practically the same. You hold more heat in the pipe so the 14.7 does not fight in return too soon... Cat fur in the throat is a ball of kennel cough is cough up the goods you are going to lose HP. Heat moving out the pipe is a tuning tool. You let 14.7 back in too soon, she nose dives. WOT WAR U Thinking? is Love racing others for pinks, (not my pink... your pink key ring is say brake fast of champions?)

 

Most, if not all 96 and newer vehicles have downstream 02 sensors.

When I had the MBRP 3.5" SI/SO catback on my truck my HP and TQ numbers were higher than another member that has the Corsa 3" SI/SO exhaust. His truck also had High voltage coils, UD pulleys and E-fans. Other than that his truck had all the same mods as mine and his was also dyno tuned by Mike Troyer as well. That being said I don't believe that a bigger sized exhaust causes a loss in either department. The only true way that this can be confirmed is to confirm this on the same truck.

 

My dad had one cat under his ford ranger. When he started the truck the cat blew up everywhere! It was so messy. Guess thats what happens when one jumps into the ol fan belt and get slung around and around and around.

 

I, in the "ABSOLUTE" believe that a bigger sized exhaust causes a loss in either dept. The only true way that this can be confirmed is to confirm this on the same logic that pumps my veins.

I am small diameter pipe and I am running down a pipe cause my air is hot and fast moving. I now enter a larger pipe, I lose that speed and enter a larger area to slow my speedown = Eye Rest My 14.7 Pee Yes Eye have some basics like better walk yours in the absolute simplest form or I am going to act like a fan belt and you the poo sea cat converter.

 

Until proven otherwise, it's truly an unknown... but I will be taking my truck back down to see Mike again to have him revise my tunes for the new catback. Then I will see the difference the two pipe sizes have my truck. I am betting I have lost in both departments with the new 3" Corsa.

 

alright i cant even comprehend what 3wV is tryin to say..... but i can say without a doubt that fluid flow from a small pipe to a big pipe is goin to loose velocity, (yes air is a fluid in case some people didnt know), its the equation of continuity states that VA = VA, velocity times area of one pipe (for this example ) = the second velocity times the area of the second pipe. for this equation to be true if velocity goes up area goes down in the next pipe and vice versa, i hope this clears this up a little bit, i think it is what the agruement was

anyways its laws of physics i should know im a engineering major