First off, I apologize if this is dumb question, but I don't want to believe a friend who may be wrong when it comes to replacing my exhaust.

he said that High flow cats are pretty much the same as hollow/dummy cats that they run & perform pretty much the same.. is this true?

Also are the O2 sensors before or after the cats? if I put in 2 dummy cats, will my check engine light turn on? and can I replace the center resonator with a high flow cat?

Thanks.

 

Most high flows do a decent job at reducing emissions, I ran one as my only cat on my old 87 supra and passed the emissions check just fine. However, they are still a restriction to a degree. If you have to pass emissions, get high flows, if not, just get test pipes. No cat>any cat from a performance standpoint.

 

Where can you find high flow cats for the SC400? I've searched and searched but come up with nothing! I need to replace my driver & passenger side cats, so now's the time to upgrade!

 

OBDI or OBDII, the general layout of O2 Sensors are right before the cat (after the combustion side of the head) and after the cat. The primary ones monitor the fuel mixture as it leaves the engine and the secondary ones monitor to see if the cat is functioning properly.

 

Sorry to threadjack but I got a good question concerning the O2 sensors, since the IMF headers only have one hole for the O2 sensor, what do you do with the other 2 (pre-cats) this is for a 93 SC400

 

Hy Meanshyguy,

i will install in the spring the IMF Headers, the 2 O2-sensors was original before the catayltic come in the IMF Header, the 2 other 02-Sensors (Check sensors) will i install after 2 small Magnaflow Pre-Converters and one big 200 cell metal catalytic (i have a 3 Cataytic SC400) to have no problems. i will weld on O2-sensor bungs.

Here a picture (paint helps *gg*)



or maybe you can use a O2-sensor Simulator and remove the 2 check-sensors complete.

greets

Tom

 

Thanks for the help

 

I say don't go cat-less. I did that for a while and the car just stunk. As far as High flows, they are usually universal and will need to be welded into the exhaust. They DO help. Also people say they are restrictive to a degree but talking numbers you will only see low single digit gains if you go cat-less anyways. Not worth it IMO.