Well my cat is rattleing pretty bad and I have decided to just punch it out till I get my turbo project all worked out. I'm kinda curious if anyone has done this and gained any noticable power? How was the sound?

Thanks in advance

 

i'd like to know aswell....

 

i did this my celica altrac turbo ... i mainly just made it louder and a little more power but i have a feeling that since it was turbo the gains were more noticeliable.
LexusFiend

 

LOL......this DIY mod goes in the same section as the "cut springs" =)
If you plan to replace it before your next SMOG then go for it.
It gives you a little top-end power at the cost of a few ft/lbs of torque.
The goes a bit towards the throatier rumbling of a muscle car.

 

whats the easist way to do this?

 

If you have a hacksaw, cut the pipes on both sides of the CAT (make sure not to mess with the O2 sensor) then take a breaker bar/hammer combo to the plates on the inside.
Make sure you get all the pieces out so it doesn't rattle like crazy.
When done, you should be able to see right through the CAT.

Honestly, I don't reccomend this because:
1) It's illegal
2) You usually get some kinda rattle anyways (qtb33 is already rattling so he might as well)
3) You have to go to a muffler shop to get it welded back on and either:
....3a) You get pulled over on your way to the muffler shop because you're running open headers
....3b) The shop tells you that they don't mess with SMOG regulations and therefore cannot take the responsibility of welding on a busted cat for you

 

Lol, i like how you put it what about using clamps and some pipe?

 

Why not get pipes made that have flanges on each end, so you can remove the cat and bolt the new pipe in? I'm interested in a set of cat elim pipes for my sc400... I live in cali so shops here won't make them for me.

Also the exhuast flow through a cat with no guts is not desirable.

 

Because it's free.

New pipe requires money, which I currently do not have.

But I do have a cat that rattles.

This annoys me.

Free rattle remover makes me happy.

 

i agree with the guy who said to replace the section but why not just get a new cat and have it welded. it shouldnt cost more than 75 bucks worth of parts then 20 or so to get welded (u can get a universal cat from jegs.com for any motor out there). by punching out the cat your going to cause turbulence in the exhaust system which in turn will create power loss. people claim to make power off punching it out and such but the difference in power gain isnt noticeable unless your turbo which in that case you should just have a bigger downpipe and cat. i dont see any reason to pollute the earth even more for 5 hp. call me a tree hugger but test pipes and hollow cats are for track only cars IMO. i've owned multiple turbo setups and always have run cats for the reason of being legal for one but second because even if we are going to be dead by the time it really affects the earth it still doesnt make it right to pollute like that...its like the smoking laws going in affect across the nation where u cant smoke in restraunts...well people dont want to breathe carbon monoxide from a tail pipe either...but again its just my opinion and some fact for u...its ur decision from there.

oh yea i forgot about the maximum penalty of $20,000 for being caught having no cats.

 

These are all good points, and I agree with them. It's just that I can punch it out for free, or weld in a pipe for free possibly. I would just rather send my $100 on something more important, like debt, or food.

Oh and even though that my be the max penalty, 99.9% of the time you'll be unlucky to see a fine over a couple hundred. Which may seem to contradict my previous statment but this is why I just want to punch it out. In NE, IA, SD, if you have something there that resembles a cat and isn't any louder than any local redneck mud truck(which prolly dosn't have mufflers let alone a cat), then that good enough for them.

 

I asked a guy at a muffler shop about taking out the cat. He said better to put a test pipe in it's place if you are looking for HP gains. He said in our V8 it should gain aprox.20 hp. with a test pipe. I don't know if this is true or not but that is what the muffler guy say's.

 

I dropped my car off today for h pipe install. I'll test the gains with the G tech. I thought about what you said VIP, it isn't cool to polute for no reason. High Flow cat for under 100 bucks, in this case two cats, but still. Test pipes would probably be less than half the $$ of new cats, but to you want to be a stinky poluter?