I just installed a K&N drop-in and a Megan Racing cat back.
Car feels noticeably slower in 2nd and 3rd gear. I did put on 16" wheels with 205/50/16 tires as well. I realize these may make the car accelerate more slowly vs the stock 15s. Car seems slower still after the cat-back install.
Could the cat-back actually have stolen HP from the car? I did have it professionally installed at a reputable shop.

 

What cat back did u use? I have 205-50-16 as well, and that 's a good reason to feel the car became slower.

 

Megan Racing cat-back

 

There should be no reason why it would decrease power. It will only INCREASE your TQ unless they were using a 3" or larger diameter pipe on the Cooper.

 

Heavy wheels? Otherwise, I have no idea. My Borla woke my car up a bit when coupled with the DDM.

 

Make sure and check for exhaust leaks

 

the power may not be felt immediately down low in the rpms. most of the gains should be top end. do you mainly drive down low?

 

Good point. My car feels more free through the revs with the Borla it's mainly felt at about 4k and up. It'll cleanly pull to redline where as before it sort of lagged up there.

 

The Catback is not stealing power. Please check for leaks and visit, http://www.1010tires.com/tiresizecalculator.asp and run the numbers to see how you may have changed the way the MINI drives without knowing it.

I made the change to larger tires for comfort and did it knowing that I would give up some "power" off the line. But it's worth it since I have smaller R-comps for AutoX.

 

It's the wheels, the 15" with the 175/65-15 Conti's really make the Cooper pop off the line.

 

I did feel the "loss" of power when I switched to the different wheels/tires. Seems like a noticeable loss of torque after the cat back install. I also thought about an exhaust leak. How do I check for that?
Thanks for all the thoughts.

 

You'll be able to hear it. It'll sound like air leaking (almost like a hiss or pop sound) from one of the joints in the system.To put it one way, instead of making noise at the back through the muffler, it'll be making noise before that.

 

You should also be able to feel it. Get the car in the air enough to be able to slide under and move your hand around the joints in the system. Don't touch anything (hot!), and make sure the car is securely in the air - jackstands, not just the car's jack or even a hydraulic floor jack by itself.

Btw, I will never trust the car's jack again. A friend was working on a MINI, sitting at the wheel well, with part of his legs just under the car. The car was on the car's jack, and it bent, coming down on his leg. He is recovering. My apologies that I don't have all the details.

Zip

 

Maybe our friend is right. The Megan Racing cat back for the Cooper has 2.25 inch piping, and that is definetally too much for a stock Cooper, when stock piping is 48mm!! And Megan is 57mm! I would say it loses power for sure!

 

This is the 1st and only report of power issues known to AXC or Megan Racing with 100's of systems on the road. There are other R50 systems with 57mm pipes without reports of less power.

The issue is not the Megan Cat Back.

 

Ι don't know what is the issue is for sure, but definetally a 57mm pipe for a Cooper is totally wrong. I don't know where this choice was based on, but the best exhaust brands out there don't go further than 50mm.

 

I installed a Megan a few months ago and definitely did not experience any power loss. Not really sure I gained any power, though. The sound is what I was looking for and I certainly got that.

Fritzoc: I know it sounds dumb for me to ask since I'm sure you took this into account....are you running your A/C now that is hotter outside when you may not have been before? There's nothing that kills power on an MC quicker than hitting that A/C button. My car is a hoot to drive...till the Air Conditioning is switched on...then it's just a dog. You really pay for comfort in this car. I usually decide to roll down the windows and sweat....you get to hear your Megan better that way anyway.