Well I have an idea for a custom exhaust, I want to take out the stock exhaust, an put in a straight pipe, with no Catalytic an only one resonator, and maybe do some custom tips or something, the picture below explains everything, what do you think?

 

Resonator in back will be very high pitched and annoying sounding.

Also, you will need to cut out the battery box and relocate the battery to the trunk.

 

I just did a custom "one-ball" with a flange that lets me replace the stock muffler with a 2.5" race muffler.

The race muffler (dynomax magnum race bullet) is way too loud ... even for track day use only. Deep and mean sounding, but super loud.

I would suggest using a resonator, and a larger muffler to help quiet it down.

 

from what i have read running mini's without cat's isn't such a great idea. It seems that the mini's ecu actually takes samples post cat so if you remove it you are going to end up with your ecu running improporly.

Something to look into.

erik

 

right i forgot the betterie box...:(

 

Everything I've read suggests that the only things the ECU reads from the post-cat sensor is the temperature to ensure the cat is working properly and the voltage on the heater to make sure the sensor heater is working. The ECU does not use either of these to control A/F or any other critical engine management feature.
My personal experience confirms this (I have run without a cat, and there's no detrimental impact on the engine managment.)
cheers,

 

i hear what you are saying and im sure that from your research you have proven that there is no harm in your case. however I was kinda basing my info on what Randy had posted on this link.

http://store.webbmotorsports.com/ind...b9d916f83d7b00

If you scroll down to the last paragraph you will see this.

Quote From The FAQ from Webbmotorsports.com.


Why do you only use headers that have a catalytic converter?

Because I care for the environment - just kidding (not that there's anything wrong with that).
This question goes to how the MINI determines the A/F (Air/Fuel) ratio. There are two basic functional modes the ECU: open loop and closed loop. Closed loop is your friend, as it uses real time, actual fuel burn to determine the A/F ratio. This is determined through the O2 sensors, located in the header. The spent combustiable mixture passes out of the cylinder head and into the exhaust system. The O2 sensors can tell the ECU what the fuel ratio was, and the ECU trims accordingly to maintain the desired ratio. OBDII (On Board Diagnostics II) uses the O2 sensors to monitor catalyst efficiency.
Open loop is used when the O2 sensors can no longer handle the flow rate. This is pretty acuurately described as a "best guess" A/F determination. It is a very accurate guess, but real time data is always the best.
The MINI has two O2 sensors, one pre-cat and one post-cat. The sensors measure the temp difference and convert it to voltage, which is monitored by the ECU. Because of the OBDII, it needs to be sure the cat is functional. If there is no change in voltage, the O2 sensor assumes it has failed and the ECU functions in open loop.
So, the reason I use only cat-equipped headers is so I don't lose the accurate closed loop ECU function.

 

Nope, you need only worry about the first one, it is very important as your computer works on your air/fuel with that one. The post cat tells you if your cat is working or not, but will throw a code, even with the o2 sim....

And it will be loud and annoying, just running without the cat made it hella loud and noisy. If you want to sound like a Civic, go for it!

 

Randy's post says nothing about the role of the second o2 sensor--and as TampaMCS says, it's the first (pre-cat) sensor that tells the ECU how to adjust the A/F. The second, post-cat sensor does what I said, which has nothing to do with open, or closed-loop operation and A/F.
And just for the record--although "sound" seems subjective, when running cat-less, my MCS sounds nothing like a Civic Ricer. I actually heard a Subaru WRX-STI and a Mitsubishi Evo going after it recently, and I could easily have joined in the chorus and been in tune. I don't think these cars are what people think of as Ricers...nor is a MINI, stock or modified.
cheers,

 

I would listen to a MINI with no cats and just a resonator before making any statement like that.

My car sounds meaner and deeper than any 4 banger ive ever heard.

 

Post deleted because i found some white sheets on the sensor layout and what they read in which order...

tnks

 

What header are you using?

 

I'd like to do a custom header into a straight side exit next to the wheel well. Maybe then people will pay attention to me.

 

If what you want is for people to pay attention to you it's a cheaper and easier if you just wear your underwear on your head. No header, no custom exhaust, just a headfull of drawers.