Just ditch the cat may pull a engine light but will have better flow.may c like 5 hp gain.

If it's performing properly it doesn't really cause a hp loss. Just keep it in there until you get a full exhaust system.

If you're talking about gutting a stock cat, that's a bad idea. From what I've read about that, you can actually hurt flow due to the design of that cat. A high-flow cat is an option, and I've been down that road. I have a DP with a high-flow cat and a DP without. Both Apex N1s. The mid and top-end I gained back from using the cat-less DP was very noticeable. Power in 3rd would fall-off at 6800 with my current mods with the cat. When I switched back to cat-less, it revs to 7500 in 3rd and wants to keep going. People say there's no loss in power. I cannot disagree with that more.

Hopefully, this can help you.

so when you used the cat apex you had more power then the cat-less apex?

well since you're not from california ... go for it ...

heres a trick straight through fake cat ...

Catalytic Converter

Alex Bland said:

so when you used the cat apex you had more power then the cat-less apex?

Click to expand...

Edit: I can see how you read my post like that. I fixed my post. I made more power with the cat-less DP. Much more top-end and better mid-range.

Why not buy a cheap SS ebay exhaust? They can be had for a bit over 100$.... full 3".

weld a pipe on there

I wouldn't do it on the stock exhaust, it just isn't worth the trouble and will probably run worse. If you are talking about on an after-market setup, it may be worth it.

I currently have no cat with my 3" downpipe and cat-back exhaust. The only reason I have it this way is because it's far cheaper to buy a cat-eliminating downpipe then one that allows you to use a cat. I just recently installed it so I haven't had to have it inspected yet, but when the time comes, I'm going to buy a high flow cat and take it to an exhaust shop. I plan to have a section of my downpipe that is the length of the cat cut off. I'll have another flange welded on to the end so I can simply swap that straight section for the cat when I get it inspected.

If you decide to go this route I think it's worth it to eliminate it.

It won't hurt flow if you cut it out on a stock exhaust system, the stock exhaust is restrictive enough.

Just cut it, get a straight peice of pipe and two exhaust clamps from autozone and bolt it up. Then scrap the cat and earn a little money and gain a little power.

habitatguy187 said:

It won't hurt flow if you cut it out on a stock exhaust system, the stock exhaust is restrictive enough.

Click to expand...

Who said that? Gutting the stock cat disturbs flow-not cutting it.

midnightprod said:

Click to expand...

Way to help the guy out. And thank you for the further demise of our forum.

I have a new 1g Megan Racing resonator test pipe that I'm selling. Some cops will think that's cat.



PM me it you want it.

Easier way to "fake it" take whatever size pipe it is and punch it threw the cat....but i dont suggest it. Just cut it and get some stock diameter pipe....i love mine out.

i say go straight pipe ... i have a 3 inch cat back greddy exhaust... i took out the resonator n took out the cat.. replaced both with straight pipe... sounds more beasty n u will feel the difference it runs so much better without the cat but it also smells like hella oil ... jus keep ## windows up u wont smell it... n after i put the straight pipe on i raced my lil bro on the freeway he has a srt-4 wit a CAI... only mods i really have is a INJEN intake and the straight pipe... we did a 60 roll n stayed side by side till we hit like 120... did hella good against a srt4 wit jus those mods so ya go straight pipe if u wanna go fast

yes get rid of it. You will notice a lil more but not that much with stock piping.

Alex Bland said:

Just for a little hp gain and air flow? also how much hp gain might i get.

Click to expand...

it would only help f your cat is clogged. keep in mind that it will throw the CEL if you run straight pipe.

take it out

Take The Cat out If Your Running Stock Piping And You Car Is Running Fine It Will Give You A Bit More

get rid of it i wouldnt spend to much money on piping and such with stock exaust i would gut it and wait untill you get 3" turboback or whatever you decide to go with and do a strait pipe with muffler no cat and weld the shell of the cat over the pipe for legal reasons

High Flow Catalytic Converter Dyno Tests

Catalytic Converter Removal - Beat the Law - Import Tuner Magazine

I think the gains are being seen from ancient clogged catalysts being replaced with 3" pipes. I've yet to see a back to back with a high flow 3" compared to a straight 3" tube. After seeing a high flow 3", it appears there is more flow area in a high flow 3" cat than a straight tube. The only real pressure drop is going to be from turbulence introduced while going into and out of it, which should be tiny compared to any muffler put into the system.

Anyone care to try?

cat and exhaust restriction makes a big difference ..
heres a comparison of my car s16G at 17-18 psi ...

please note the 60mph mark about 6250 RPM for reference

2nd gear pull and note how the " restricted piping" test peaks before 60mph (6200-6300rpm)
and the " no cat" test continues to make power to 6600 rpm ...



just notice how much it was gained up top with the less restrictive setup

I hate to break balls, but that's a 2.25" down pipe and oem cat with a crush bent 2.5" exhaust and muffler compared to a 3"dp, mandrel bent 3" exhaust, and a 3" muffler. That's not a modern performance catalyst compared to a straight pipe.

Definitely cool that dynolicious can pick that up though.

I have 3" front to back no cat sounds awesome & better engine response, have never kicked a cel. The only down fall for me is fighting a bit of boost creep. well worth it.