Has anyone tried this? There should be some performance increase.

 

If it is boosted, yes.

 

which cat? front or the ones in the mid pipe?

 

both are illegal, good luck finding a shop to do the work.

 

I had my exhaust finally installed a few weeks ago. I had a complete cat-back done. 2.5" mandrel bent. I had the 2 secondary cats removed no problem.

Honestly, I can't tell if theres been a performance increase or not and my mileage has been affected only because I've been constantly flooring it to hear the roar

 

hahaha.... it's like saying you can't copy a key that has a "do not duplicate" on it.

removing the all CATs after O2 sensor.

 

Yes is the answer, Your details are here.
https://www.clublexus.com/forums/sho...custom+exhaust

 

you MIGHT get 1-2hp

 

linh811 more like 8-10

 

for removing just the secondary cats and leaving the the stock mufflers?? show me a dyno

 

yea, its exactly like that, except one doesn't carry federal penalties anywhere near as steep as the other. you also get a key made because you need a machine. you get your exhaust installed because you're too lazy or stupid to do it yourself.

wonderful reasoning you have.

 

umm so you have the tools to cut and weld in your garage? good for you. as for me, I'd rather pay someone to do, personally its not worth my time. Just like I pay for cleaning/maid service and lawn service.. same *****...

 

I'm sure there is an increase, but noone has done any significant testing. However, the best dyno results I've seen for exhausts that retain the secondary cats is about 5 HP, and the best results that I've seen for exhausts that eliminate the secondary cats is about 10 HP. I figure that means that there is probably about 5 HP to be gained by removing the secondary cats.

The problem is that there is a maximum $10,000 federal fine for removing a working catalytic converter. I don't know what the minimum prison sentence is, but that would be MUCH more significant in my book ... especially federal. I guess you just have to figure out how badly you want that 5 HP.

 

Where I live in Mexico, the law is so loose that the legal wording is virtually 'below efficiency' cat for replacement which happens just about as soon as you touch the gas here. I am already on my 3rd main cat and had one of my precats destroyed by bad gas down here. Here, cars that are 1991 or later must have at least ONE working catalytic converter.

Over on solaraguy.org I have seen discussion of 1MZFE Solaras that come in 2 varieties, ones that have precats for CARB, restrictive emissions areas, and others that go under a federal emissions and only have a single cat. This came up when they were talking about use of aftermarket headers that use just a single main cat.

However, I agree going catless entirely is where the big legal issue arises.

 

but there are no dyno's with no 2nd cats while retaining the STOCK mufflers. If the stock mufflers are the limiting factor, then removing the cats while retaining the stock muffler won't do anything.