Hmm, yeah good call. I don't mind having to do the exhaust shielding myself. I can just buy some exhaust shielding wrap and that should work. But you are right about the positioning of the 2 o2 sensors and the cat. From what I have read you want the cat to run as hot as possible without meltdown. So putting it factory distance from the engine exhaust ports is probably the best. And then I suppose spacing the o2 sensors factory distance from the cat would also be the best bet. I guess I have a lot of measuring to do before I decide on the proper exhaust system.
Thanks,
Marge

 

Okay, so I have the 3.4 ready to swap in. I did a whole bunch of stuff to get it ready (put on all the ORS full swap stuff), changing all the stuff that could go wrong except: the pistons, rings, bearings, front and back main oil seals, and oil pump. Everything was in really good shape in the engine, no oil sludge, clean cylinder walls, not much carbon etc. I will be putting it into my 1991 3.0L 4wd longbed pickup at the beginning of December (earliest convenient downtime). I have a couple of questions about the exhaust. I am using the custom crossover pipe from ORS (ID = 2.25") and I would like to get a full 2.25" exhaust system, the works. So hi flow cat, muffler etc. Does anyone have any recommendations? Price is a factor.
Thanks in advance,
Marge

 

stock toyota cats are fairly "high flow" by most standards, as far as mufflers, a lot of guys here on the boards like the magnaflows or dynamax, its all about how loud you want to be...

 

My main concern is performance. I don't care so much about sound as long as I am not making the engine work any harder than it absolutely has too. So stock might be the best then?
Marge

 

Are you sure your ORS crossover is 2.25"? Mine was 2.5" I think most guys are using 2.5" with a custom 3.4 exhaust, I know I did. I used a Carsound 2.5" cat and a 2.5" Magnaflow muffler

 

Thanks Dale, yeah it is 2.5". Haha, oops. So 2.5" I will be using. Which of the carsound cats did you get? I gotta get one that is California CARB compliant. I'll probably have some more questions about the exhaust as I proceed.
As always thanks for the good info,
Marge

 

Mine is a 91006, but I originally bought it for my 3.0 so it may not be the best choice for a 3.4. I have thrown a P0420 numerious times because of the ECU not liking my new cat. The URD simulator has taken care of that CEL though. My ECU is a 2001 so it is looking for 2 cat efficiency like the Ca models do.