I was wondering if I should replace both cats and replace it with a high flow ones(Which brand is best).

 

Here's a pretty decent thread on mufflers and cats flow rates. I'm trying to decide too, but I noticed that the stcok straight pipe flow rate isn't much above 400 CFM, so I'm not what the benefit of running a higher flow rate muffler or cat is worth it or not. Check it out here: https://www.yotatech.com/forums/show...&highlight=CFM

Chris

 

I'm pretty sure I will see gains in performance with two high flow.
And I am concidering a stright pipe but I still need to fool the 2nd o2 sensor o no "CEL"

 

I installed a Carsound 2.25" based on price, but that link above showed they have decent CFM numbers as well. In the Supra world, people seem to favor cats made by Random Technologies, but I went for the price.

Just so you know, it appears that when you uncork the exhaust with headers, with flow cats and bigger pipes, expect to lose some low-end torque, which is what happened on my 'runner, but the top end is better, so it's a trade off.

 

This why we dual stage mufflers like Nissan makes for some of their vehicles. They allow for higher back pressure at the lower RPM's and flow rates, which in turn provides the low end torque we love. And, then when it hits a certain RPM or flow rate it opens up entirely for maximum flow rate and power at the higher RPM's and speeds. It's an awesome and functional system.

Chris

 

Also, if you are going to run a straight pipe, this link will take you to a product that can trick the ECU for the second bank O2 sensor. It's says it's for Supras, but this will work on our vehicles.

http://store.yahoo.com/supra/oxsensimob97.html

After doing research on this subject, I've discovered there is not benefit to running a straight pipe over a high flow cat and muffler. The restriction is the straight pipe, so why not run a cat and muffler like we are supposed to, and achieve as good or better flow rates than just a plain old straight pipe?

Chris

 

Well I am going to get etiher car-sound or extremeflow cat converter. I am going to stay with the stock OD 2.25''. I have a Spin Tech Pro Street muffler which has one of the best CFM's. I am starting to feel a stronger pull above 2500 rpm's with 100 miles on the muffler and with two high flows cats and TRD headers it will be even better.

 

Where can I buy the Car Sounds cat converters for a low price.

 

Ok I just checked to see how would I put the Catalytics on and I saw that the 1st cat is VERY close to the header pipe so, when I get the high flow catalytic(I plan on replacing the whole exhaust piping anyway) can I place the hi flow cat further back about 2.25 inches from the stock cat so it can fit and would this mess up the o2 readings or am I ok if I do this.

 

I've seen CarSound cats on Ebay really cheap. I bet they are not the higher flowing ones though. I think I might have a source for the high flow CarSounds. I'll try to get some more info on them.

 

All aftermarket cats are high flow.

Companies saw the demand for a "high flow cat" so they started labeling all their cats "high flow", even though they already were. It's pure marketing, plain and simple.

 

So, can I move the cat further back or jut replace the 2nd cat.

 

I'd say it depends where the O2 sensors are whether you can move it further back or not.

Chris

 

How are there two cats? I have always thought there was one cat & one resinator and one muffler. Two cats?