Exhaust Question

[LEADFOOT]

I am going to rework my exhaust. I bought the (and I know I will hear it from Jedi) new Flowmaster super 40 muffler. Going to run 2" down pipes into a 3" Y-pipe and the rest of the way. I was going to eliminate the cat but can't find an 02 sim for my truck. What is a good inexpensive cat to run. With the flow I am going to have with the FM super 40 and the 3" pipe and the headers should I get a high flow cat? They are pretty expensive, kinda. I was looking at a regular catco 3" in/out 14 1/2" long, stainless steel, around $60. Its not high flow though. All opinions welcome. Remember I am prepairing for the wynjammer.

[OBI WAN]

New Blowmaster muffler and your worried about flow numbers??? Yeah I had too!! Caspers has the 02 stims, same ones for all 96+. ALso there are a host of so called high flow cats from Randomtechs, to dynomax ones. In reality the factory ones are high flow as the aftermarkets are. All use honeycombed low resistance cores today unlike the oldies that used pellets!

[Supercharged-ZQ8]

A 3" is a bit much, IMO. I run a 2.5" all the way, and it does nicely -- however, I have a Dynomax Ultra-Flow, which is one of the higher flowing mufflers around.

I would say that I've got a cat for sale. It's an 18" Dynomax high-flow 2.5" in/out. I was hoping to swap it out, but the pipes aren't the right size for the rest of the exhaust. The y-pipe is 2.75" and the cat-back is 2.5" and there aren't any muffler shops around here that want to even touch it (the fines associated with a not-stock cat are what they're afraid of -- and I don't have access to a welder).

[LEADFOOT]

New Blowmaster muffler and your worried about flow numbers??? Yeah I had too!! Caspers has the 02 stims, same ones for all 96+. ALso there are a host of so called high flow cats from Randomtechs, to dynomax ones. In reality the factory ones are high flow as the aftermarkets are. All use honeycombed low resistance cores today unlike the oldies that used pellets!
I looked around and can't find an 02 sim for my truck. I called caspers and they said they don't have one yet. I asked if some of the ones that look like they will fit will work and they say said, not form what we have tested. S/c said his connector is flat and he has a 98. My connector is 4-pin square. I was thinking about trying to find one for an 00-02 camaro and see if that will work.

[DeathtoRice]

http://www.o2sensorsimulator.com/ There is a universal o2 simulator that will work on GM. I just ordered one yesterday, and the guy has no negative feedback on ebay at all.

[bvr775]

http://www.o2sensorsimulator.com/

This simulator cannot be used to replace the primary/upstream sensors since those are used to create the proper air/fuel mixture.


but this is the problem we post 01 guys have been having with all sims

A 3" is a bit much, IMO. I run a 2.5" all the way, and it does nicely -- however, I have a Dynomax Ultra-Flow, which is one of the higher flowing mufflers around.



he's right you can go to big. i wouldn't worry about your cat It's one of the higest flowing cats out there. You shouldn't set off any mil lights if you leave the sensors.

[DeathtoRice]

Why would you want to replace the upstream sensor? That simulator gets rid of the one after the cat. That is what the guy is asking, I think. And it WILL set off the light if you remove the cat and leave the sensor there. It did for me.

[bvr775]

the post cat sensor can't be removed unless you delete it with a tuner program. I'm not sure with one of the 5 o2 sensors is the upsteam sensor. I know on the 01 to present GMs you almost need tunner programe if you start messing with any of emmisions because some programing changes from previuos obdII made these years more sensitive to changes. The obdII dosen't tell you there's a problem it tells you if there may be an upcomming problem so if you mess with one thing you have to fool the rest of the system into thinck it it's working within + or - x % of the programed feild.

If you leave the sensors you shouldn't have a problem. The worst I've seen is a lean condition setting off the mil light after 1000 miles or so, but I've only seen this once in the a 2.2 and that was an easy fix with the addition msd box.

[LEADFOOT]

Why would you want to replace the upstream sensor? That simulator gets rid of the one after the cat. That is what the guy is asking, I think. And it WILL set off the light if you remove the cat and leave the sensor there. It did for me.
Yes I am talking about the after cat sensor.

[Maximus]

Before I go any further tell me if your plug looks like this.And yes ive used o2 sims on 2000 up OBDII vehicles with no programming needed or issues caused by them.http://www.sicgmtrucks.com/forum/attachment.php?attachmentid=832&stc=1