I am wondering what the limitation is of our stock cats. I was trying to sell my TT kit but I think ill probably end up getting it installed.

Its a 700BB kit, but I was wondering how much our stock cats can handle and if flow will be sufficient?

I am looking for about 400whp and I would like my car to still be able to pass emissions etc. in Hawaii we dont have emissions checks, but I might be moving and not sure where so I would like to be able to pass just in case..

Right now im planning to just weld an extra wideband bung on the stock cats so just want to make sure itll work ok with FI.

 

Put the bung on before the cats. I think you can make 400 whp (Dynojet) with stock cats. I made 400 whp (DD, likely 440 Dynojet) with Fast Intentions HFC and the 700bb kit. I then put on 200 cell cats (have these for sale cheap if you want to fabricate a pair of custom cats) and made 436 whp DD. I made 480 whp DD with test pipes (520 Dynojet).

I am currently running 100 cell cats but have them further back also - haven't tested the power on these - much easier to remove further back in the exhaust.

 

was this all on the same amount of boost?

 

easy solution is just keep your stock cats handy in case you have to pass emissions and run straight exhaust until then... turbos don't like cats man

 

cats are a pain to change out though. jdm-v35, that was basically max power on pump gas at any boost level. I found that with cats, torque might increase but peak whp would drop fast, even with more boost. So I wasn't getting an increase in power past 12 psi with stock cats...

 

ah i dunno what to do then. I dont wanna run test puipes due to noise levels and emissions since I plan to move soon. Since my goal is only 400whp though i think I should be alright on stock cats for now.

 

I am not sure how involved you are trying to get with your turbo setup but maybe this setup I am looking to do will help solve some issues I am still looking into it.

I have 3" down pipes and a greddy cat back exhaust system. Since my downpipes take the location of where the stock cats would sit about I have moved the location of them.

I am going to cut a section out of my Mid Pipes the part after where the flanges are that connects the down and mid pipes. When I cut out a section of that I will weld on a flange on each side. This way I can put my cats back in when needed for inspection but then after just take 10 mins to pull the cats out and I just put the straight pipe back in and I am good to go.

Now of course I am not using factory cats but for the visual inspection this proves that there are working cats on your car, the guy I know pretty well at my shop said he would pass it with assuming I have no CEL either. The other thing you might need to do is and I am not sure yet is extend the o2 sensors to get to where you have the o2 bung in.

 

If you have a reflash that has the O2 CEL turned off, you can just leave the sensors on the downpipes... Or just use non-foulers.

 

since im not going too extreme with this I am going to leave the stock cats in for now and maybe add test pies/hfc later on.