exhaust questions

[Maximous]

can we remove our cat converters on our trucks, where is the sensor thingy, and does anybody have an idea as to what our trucks would sound like with headers and a or a pair of flowmasters, i was just planning on replacing my stock muffler, but i might just go with true duals coming thru headers, but, can we do that or will that mess my computer up even if i get a programmer thingy, also is that gonna hurt my low end torque, i ran my old blazer (hotrod 2wd 2dr s-10 w/350ci/+-300hp) and i didnt lose anything, well except maybe my hearing, but it had more bottom end then it did before

[F9K9]

Am definitely no expert but, I believe we have 2 or 3 O2 sensors and their removal will throw an SES light.. There's simulators ($50 each) out there to fool your computer into thinking you have them but, the cats are pretty free flowing compared to the ones of the 70s. The HP IIIs will not help you in that department. If AL doesn't have annual vehicle inspections you might want to think ahead and if you move to a state that has inspections, you'll not be able to pass them. Would toss the money into a piggy bank and save for the "lift" we all would like to have like KC's. Just my late friday night 2 cents worth.

[F9K9]

HJ strikes again! Thanks for the avatar!

[Maximous]

that is a good point, no alabama definately doesnt have emission checks, if we did im pretty sure we'd lose half of our police cars neither does florida, that's the only place's i ever want to live, but i really have know choice where i live, until i become civilian Law Enforcement of some type, which may not happen if i become an officer, but yeah the lift is defin the future piggy bank, as soon as i have little warranty left, about 1000 miles or so i'll put it on, so with my driving habits, maybe a few months, my 03 sunfire had like +25,000 miles on it, i got that car in late july when i got home from basic training, this july i had my truck, not real sure when i got rid of the car but i had also been deployed in that near year i had been driving it, so there is 3-4 months that it didnt move at all, i drive alot

[HenryJ]

can we remove our cat converters on our trucks, where is the sensor thingy... i might just go with true duals coming thru headers, but, can we do that or will that mess my computer up even if i get a programmer thingy, also is that gonna hurt my low end torque...

I would say yes you can remove the cats. However there are some things that may need to be done to compensate for their removal,
The O2 sim that Reed mentioned for the last sensor for sure, and some extra muffling unless you want things WAY loud.

I think ditching the pre-cat is a decent plan. It is prone to failure and requires no sim.

Our cat is a good one , as cats go. It is a 3" in/out honeycombed highflow design. You really don't gain much with it's elimination, IMO ,at this time.

The whole "back pressure" worry gets pretty blown out of proportion, if you ask me.

Exhaust changes can change the rpm range where power is developed.
Even a straight pipe the correct length can offer enough back pressure. Now a 25' tailpipe may not be very practical , if that is what is required

I guess what I am trying to say is , that there are other ways to get the power curve in the range you want.

IMO, the stock main cat offers plenty of back pressure. Running with a mufflerless catback would be intolerable after a while, but with the addition of a free flowing muffler to cut the sound, they do pretty good.

[Maximous]

so heres what i got from that

no cat = no good
no muffler = no good
no pre-cat =good
leave stock cat = good
throw stock muffler off biulding = priceless

no really take out the stock pre-cat and muffler, replace with flowmaster and leave stock cat

[HenryJ]

I would add to that:
Bigger pipe = deeper tone

I have heard that some people who added just a free flowing muffler ended up with a "tinny/ricey" sounding exhaust. I can not vouch for this, though.

One thing you may have missed is :

IMO, the stock main cat offers plenty of back pressure.

So anything afterwards is just to quiet the system, so make it flow as best you can.

I am sure that I have said this somewhere, but keep in mind that flow is better over a hot surface, so bigger pipe is not always better if it does not get hot enough to flow and also burn out the moisture for a longer system life, smaller pipe could actually be better.

We have 1.9" head pipes that merge to 2.5" to the cat that is 3" in/out , then necked down to 2.25" on out.

I have run 3" from the cat back , delta flow muffler, exiting the stock location. Two other s-series from here have done the same thing with positive results.

IMO, it is the "sweet spot" for the 4.3L

Now if you do lots of short trip stuff and unprotected exhaust systems don't last long in your area, just replace the muffler and retain the stainless steel stock exhaust. The gains will not outweigh the cost of multiple new exhaust systems.

[Maximous]

Now if you do lots of short trip stuff and unprotected exhaust systems don't last long in your area

i dont understand what you are saying here, please further your explanation

[F9K9]

If you usually drive under 10 miles to work, store or whatever, the water that normally condenses in your exhaust will not get "burned off". Water will cause the system to rust quickly requiring replacement. From what you said about your driving habits, it should not be a concern.

[HenryJ]

Now if you do lots of short trip stuff and unprotected exhaust systems don't last long in your area

i don't understand what you are saying here, please further your explanation

When you start the vehicle it takes some time to warm things up and burn the condensation from the exhaust system.
Colder climates , high humidity, salt air, system design, etc. can contribute the the deterioration of the exhaust system.

If you live in a dryer climate, drive more than 10 miles each time the vehicle is first started from cold. Then the exhaust has time to warm up and burn the condensation out and the system lasts longer, even if the pipe size is larger taking longer to warm up.

By unprotected I am referring to a lack of stainless steel tubing. Aluminized pipe does offer some protection, but not as much as the stock system offers.

Check out some of the neighbors mid to late '80's cars to see how their systems are holding up, or ask your local muffler shop. If they are good in your area, you can get away with most any system.