So I got an OBX header and I'm trying to figure out whether I should weld in the cat, or just go without it. Only thing is, i don't know how to weld that much and I'm worried if I lose the cat the car would be super loud. I'm already using the one ball thing and it's not that loud at all but with the cat missing I fear it'll sound like a high school kids Honda...

So how much of a noise difference would it be driving without the cat? If its not that much of a difference I'll just leave it off. I want it to flow better without the noise... Any suggestions?

 

High Flow cat? Without a cat, it will be louder and throw a CEL. If you don't know how to weld, then I suggest taking the car to an exhaust shop.

 

Keep cat... The MINI likes the back pressure and you might actually fail emissions depending on your state. Don't know if Florida checks...

 

How is that possible? The whole back pressure thing is supposed to be a myth

 

OK, pull it off and find out. Every MINI that I have seen a decat done to immediately put it back due to poor performance. They lost torque after doing it. Not sure on an R56, but the R53 likes the pressure.

and...

If you have emissions in your state, you will likely fail.

 

Hmmm interesting point... I also though about grabbing a hi flow that bolts on instead of having to weld (laziness LOL) so I don't have to cut stuff.. I did the one ball mod and since then I tryna avoid welding

 

Every engine needs some back pressure. Finding out the perfect amount is the hardest part. The only engine that DOESNT need and you dont want to have is on a turbo'd vehicle as it runs off of exhaust gas and you want to expel the discharge air as quick as possible. I dont run an exhaust on my Cooper and I lose so much torque and umpf....

 

Takw it to an exhaust shop, keep your factory CAT, the little yellow light on the dash is annoying.

 

Take off the CAT and go with one of these.
http://http://www.o2simulator.com/in...c27b24f67fd773

I've been running one of these for the past 4 years and no problems and no CEL. Note: car will be louder at higher rpms but the sound at idle didn't seem to change.

 

I dont have a cat. Feels the exact same in power to me.