I took the cat and muffler out of my MC. Weird thing is I expected that to give me more power but instead it boged it down alittle. does running catless mess up the compression in a minicooper? I've never heard of a car running better with backpressure...

 

Im no expert, and most likely completely wrong, but possibly, the ecu is not used to it.

 

Get a header put the cat back on and stay close to 3" pipes is what I've heard is how to get the best backpressure. The weak link in the process on these cars is the head, which needs bigger exhaust valves, so I'm told.

BTW: no cat on the street is a $1500 EPA fine. just an FYI

 

Good point without a simulator the programming will bog down as the pre and post cat readings send the ECU into closed loop not open loop which will also hurt preformance good call.

 

1500? haha dang well I left the muffler hanging in the back so it looks like an exhaust. I didnt even think about the ecu..

 

Was it bogged down at higher RPMs at WOT? I know on the S version, the o2 isn't used while at WOT. With a lower restriction exhaust set-up like you describe, you're possible going to gain some top end, but definately going to loose bottem end torque.

 

no it was lower end rpms like from the get go that it was bogged down. High way seemed fine except in 5th gear if I used full throttle it still wouldnt go anywhere at 4,000 rpms.

and what does WOT stand for?

 

You need some backpressure to generate torque in low RMP in a NA car. It is natural that you feel a loss of power if you remove the cat.

 

Backpressure is a highly debated subject. I've read plenty and still don't know what to think. It's long, but if you want a look at one side of the argument spend some time with this thread.

 

I've read plenty on it myself. Im with the pro-less backpressure = power. however this is making me think differently.

 

I was always taught.....NA = you need "some" BP........Turbo applications = No BP

 

ya I never thought about that. I guess it helps turbo and superchargers from their highflow. Im tempted to put it back but I dont wanna loose the rumble >___< next paycheck ill have my money for the exhaust. but I still dont see how a high flow exhaust can help hp??