I recently bought a catless downpipe for my 2011 Mini Cooper S and I’ve noticed a pretty steep power drop when it’s wet and I was wondering if this is harmful to the motor or if it’s like an intake where it just takes away a little power whenever it gets wet. I didn’t know if the downpipe would make the motor take on more water?

 

"--- when it's wet ---"? When what is wet, atmosphere, DP, motor exterior? "--- make the motor take on more water?" Coolant is a closed system, what's taking on more water?

 

Im just talking about like when it’s raining or going through a car wash. Will the catless downpipe take in more water and cause any issues? Bc I notice power loss whenever I’m in those situations.

 

DP should be "waterproof" --- external water is not supposed to be able to get into the DP, or anywhere else in the engine. Possibly your air filter housing has a plugged up drain hole. Or an exposed air filter is getting wet, inhibiting air flow. Just changing to a catless DP shouldn't cause a performance change in wet weather, but you should consider getting a stage 1 tune to compensate for the changes it will cause.

 

I haven’t had this problem whatsoever until I had the downpipe installed a few days ago. Could anything have been installed wrong or anything messed up during the installation that could cause weather to be an issue?

 

Maybe check for bare wires on the two DP O2 sensor connectors. Then check the air filter housing drain hole, it's not a difficult task. Otherwise, you're looking at a tune to compensate for different air density in the DP. Usually, when converting to catless, a code is thrown, indicating the ECU is seeing different quality air. Tuning can eliminate this difference. I hope you live in an area that doesn't require a catalytic converter. License renewal can be a problem.

 

Ya, I’m in Ohio so I’m not super concerned about not having the cat. There’s also nobody in Ohio that knows how to tune a Mini Cooper unfortunately and I’m trying to scrape up the funds to send my ECU to MarioKart lol