That is amazing to me. I would love to believe it. It has always been with older cars that the cats were HUGE power robbers. Removing them or switching to high flow cats was ALWAYS a good investment with the correct 02 sensors. And cheap, like 65 bucks each for Car Sounds here locally.

So then our cats on the 2003 350Z are high flow cats like the ones that come stock on late model LS1's?

I asked this a few months ago but never got any flow numbers.

One less mod and less smog trouble. Works for me, but I would love to see a flow comparison with and without cats or better yet a track run. That would really sell me. I hate messing with pre cat stuff!

If a car with intake and exhaust ran the same ET, trap and 60' as one with no cats I would be truly amazed! Same car except the cats same track same driver and same day.

 

On N/A cars, cat bypass/test pipe/straight pipe will result in losing back pressure results in losing low-end torqueHowever, high-end horse power can be gained.
It will work much better on turbo cars, it helps the turbo spool up faster and at the same time gains high-end horse power.

 

That's just a rule of thumb. Reality does not always follow suit.

 

But what he is saying (increasing high end) is track proven here locally, better ET's every time.

That is why I increased my exhaust piping size, for my Nitrous and in case I go Turbo, Muffler Tech told me the same thing.

With FI increase the exhaust size.

 

Of course that is proven everywhere. High end for the track, low end torque for driveability. It is a rule of thumb. Also, I was looking at it from the other side. This "rule of thumb" we are talking about only allows for linear change. Removing/replacing parts does not always provide expected results. That is all I am saying. I def. do agree with the rule of thumb but it is a generalization.

 

Well, Mr. Potato Head, I guess you're right. Without any hard numbers on the dyno, we can not say for sure the 350z will lose or gain horse power at either range with the set up. At the mean time, we will have to use the rule of thumb to predict the possibilities for of the out come.

If anyone have dynos with and without the cat, please post them. Thanks!

 

I guess if we are to use rule of thumb principles while we await for parts for our beautiful cars then we should define our goals / intentions first.

IE, I want to increase my 1/4 mile ET will such and such help

or

I want to build a SEMA show car should I add titanium headers?

The Dyno is just a tool, I have never put much stock in it's numbers for the 1/4 mile. Unlesss I lost 10 HP on a new mod or something, yikes!


As a rule of thumb of course.