Cats or No Cats???

[Billy Mild]

I'm debating between getting some high flow race cats or to go sans cats altogether. I have heard without cats the interior of the car will always smell bad after driving the car. I would prefer not to have this smell. For the small HP loss I don't see a reason not to run cats. They only will take away 5 HP.

The cats I am looking are: Random Tech 100 cell, Magnaflow Spun Cats, and MBS High Flow cats. Another option I saw someone on here do is run C6z06 Cats on their car. Is one better than the others?

http://www.summitracing.com/parts/mpe-59959/overview/

http://mandrelbendingsolutions.com/m...ace-converter/

http://www.randomtechnology.com/products.html

[WARP TEN]

I currently run without cats as Illinois does not require emissions testing. I have SW headers, a stock 95 exhaust system and electric cutouts just before the mufflers (some pix in my albums). Another reason I did not want cats if that with the length of the SW headers I would have had to cut up the front part of my stock exhaust system and I did not want to do that. When I had my Corsa on the car I did use I believe Random Tech cats. You are correct that without cats your car exhaust will smell a bit--kind of like they did in the 60s and 70s. Not too bad and usually just on cold start up. The biggest advantage to cats (other than for the environment) is that they soften exhaust noise. I would say cats can reduce exhaust sound by as much as 20%. Yet they only cost a couple of horsepower. --Bob

[efnfast]

the only people that smell my car without cats are the people behind me.

[RussMcB]

I've never heard of non-cat cars getting smells into the interior of a car. Is there an explanation of how and why?

My initial gut feeling is there must be an exhaust leak for that to happen.

Or maybe it's because gasoline is formulated differently now? Still not sure how straight pipes in place of cats would cause a smell (much less going into the car's interior).

[WARP TEN]

Originally Posted by RussMcB

I've never heard of non-cat cars getting smells into the interior of a car. Is there an explanation of how and why?

My initial gut feeling is there must be an exhaust leak for that to happen.

Or maybe it's because gasoline is formulated differently now? Still not sure how straight pipes in place of cats would cause a smell (much less going into the car's interior).

No exhaust leak, Russ. Just an excess of hydrocarbons that the cats usually eliminate. If the car is just standing on a windless day or there is a slight tailwind, it is noticeable in the car. Or if you are just standing nearby or behind it. As noted before, I only notice it on a cold startup, and usually in my garage when I back out. And if I am driving my car it usually means the windows are open.-Bob

[secondchance]

Originally Posted by Billy Mild

I have heard without cats the interior of the car will always smell bad after driving the car.

Smells bad?! To me it "smells like VICTORY!".

[mike100]

The making your car smell comment is what I take to be when you stop at a light with your windows down and you choke on your own hydrocarbons...

I ran the Z06 cats because:
1) I already had some laying around.
2) they are fairly compact for a 3" catalyst.
3) you know they have a lot more precious metal content and do a better job of converting the pollutants than some universal hi-flow mini cat.
4) oem cats don't usually clog and break apart at the slightest hint of rich running or minor impacts with speed bumps. I thought it was the best catalyst for the application regardless of cost (which happened to be cheap since I had a pair).

I also had some LS2/LS3 catalysts too, but they are flat shaped and I thought it would be a challenge to fit those in the C4 tunnel. People have been giving them away since the LS2 came out.

[batchman]

Cats are a cheap technology that works. One thing for a competition car but for the street, no question for me - cats.

In fact I even run cats on my event car, doing otherwise would stink up the grid too much. You can tell the cars that don't run them, if you're next to one within moments your eyes water...

Cheers,
- Jeff

[PhillipsLT5]

Random Tech

[GOLDCYLON]

Originally Posted by PhillipsLT5

Random Tech

Both Phil and I are running RTs. Its the right thing to do. 2nd choice is magnaflows