WhosAlex

Hello I was wondering if I could replace the center cat in my 1992 sc400 with a 2.25” pipe. I want to know if this will cause any issue or lights to turn on.

CLass of 1

No issues, it’s very common. I don’t believe the center catalytic has an o2 sensor, no worries there.

Nick

WhosAlex

thank you, what do you think is the best exhaust set up for a loud but nice sound?

CLass of 1

Best sounding is subjective, but the best flowing exhaust is:

- Stock front catalytic converters
- Stock front Y (where both manifolds meet)
- 2.5” pipe from stock Y to the rear Y (I would do a resonator where the cat is now for improved sound)
- Replace old Y with better flowing Y (2-1 merge collector is best, but any high quality aftermarket Y, such as Magnaflow is fine)
- 2.25” piping from new rear Y back to the mufflers

I believe there’s an argument for adding resonators where the stock ones are located in the rear section too. Manufacturers, like Toyota and Lexus, go through a lot of trouble to tune factory exhausts. They make Herculean efforts to ensure the system performs its best and they remove all unwanted resonances produced by the exhaust that would be picked up by the car’s interior and unibody. One of the key aspects of tuning that sound is pipe length and position of each component.

For me, it makes the most sense to replicate component placement and pipe length. So, if I was building an exhaust system from scratch I’d replace the center cat with a resonator (which the stock catalytic kind of acts like, sonically anyway). I’d also place smaller resonators in the same locations they are now. Mandrel bent piping throughout, of course.

This is what I’d recommend for the center section: https://vibrantperformance.com/catal...products_id=46

And two of these on the rear: https://vibrantperformance.com/catal...b2184e7739ae02

Measure the stock resonator length and match it up to those there.

That setup should flow excellently and sound throaty without ever being obnoxious.

Nick

RudysSC

I cut mine out in my '96 SC4 - no light, no codes, and passed CO emissions flawlessly.

KahnBB6

iTrader: (5)

I'm not sure about SC400's but for 1992-1995 SC300 California-Emission models and ALL OBD2 1996-2000 SC300's there is a four-wire heated O2 sensor on the center catalytic convertor which will cause a CEL if disconnected or removed. That SC300 center catalytic convertor O2 sensor does not directly control engine function but does tell the ECU whether or not the center cat is functioning at optimum efficiency.

Again, this may not be the case with SC400 models as others have mentioned above. I'm not as familiar with SC400's as I am with SC300's to know from personal experience.

WhosAlex

Will I lose any low end tourqe or hp if I take out the center cat?

CLass of 1

No. If you keep the front stock Y you are good. You will only have gains with the setup I recommended. Whether you straight pipe center section, or use the resonator. The resonator I recommended to you actually flows better than straight pipe.

The stock system from manifold to front Y has been proven to support supercharged setups making 300+ horsepower.

Nick