mylexusgs

Hey everyone,

I have a 2002 gs300 that is largely bone stock. I had a check engine light come on today and when I checked the codes, it came back to a failing Cat system.

My plan for the car is to go to a single turbo setup putting down between 450 and 550 horsepower to the ground. I have the ability to simply cut the cat(s) out and weld in a piece of pipe to replace them. Is there a way to keep the computer from tripping out because of the lack of cats on the car?

Eventually, I will be installing a Tanabe Medallion Touring exhaust, but for now, I just want to get by.

Thanks

TrueGS300

Yes, look up o2 extenders on ebay. Only needed for the two downstream o2s. This will pull them out of the exhaust enough that they wont throw codes. You want to keep the front two in the exhaust for the computer to see a/f mixture data and run right.

mylexusgs

Cool! Thanks.

shwalker07

I run the stainless steel o2 spacers for each of the 2 rear o2 sensors after the cats as mentioned above. No engine light and no problems but I do not run cats because I run a straight header, mid-pipe and a full exhaust on mine.

TrueGS300

Same here. Been running catless headers with the two downstream o2 extenders for months now. No codes have come from it.

mylexusgs

What headers are you guys running?

We have crap gas here in Kentucky and I think the cats are getting plugged up as a result.

Thanks

TrueGS300

They are the cheapo eBay IS300 headers.

Ethanram64

What up guys, I have a 03 gs300 and I plan to go completely catless but I live in the NYC area and as some of you may know to pass inspections are super tough over here.

i read up about the 02 sensors and how it worked for some of you guys, but I don’t have any idea what kind of catless header to get. If one of you guys have one can you please share what brand and and type it is. I also just wanna make sure I can go catless and not have a check engine light on to pass. If anyone has an suggestions for me, please let me know

mylexusgs

Ethanram64 - If you go Catless and they do a visual inspection(which, if your car is modified in other ways, they probably will), then it doesn't matter what you do with the o2 sensors, you will not pass. Honestly, there is no reason to go catless on a stock engine. I kept mine but put some o2 spacers in place to get rid of the engine light. Still get great power and no issues with my stock engine.