I just installed a jcw cai on my mcsa and there was this piece of plastic lodged in the back bottom hole. I took it out. Was I supposed to? nothing in the instructions i have found have mentioned this so I'm curious. I did a search here on nam and found that someone was told to leave it in. That doesn't make much sense to me but I'd like to know if others have taken it out or not. Thanks.

 

The reason for leaving it in to reduce noise levels at low rpm, then you get the noise (read: extra air from the cowl) when the flap opens at 4000? or so rpm. I have taken the plug out when I've installed these, but its really up to you.
--Dan

 

The plug exists mainly to create a more dramatic sound effect when the flap opens. The original air filter box had that port in place to help with airflow slightly as well as give an alternate air intake should the primary opening next to the radiator become blocked. There could be a slight benefit to not having the plug in place at lower RPMs by allowing a tad more air in, but I doubt it is even measurable. I took mine out when I installed the JCW intake as well.

 

Just bought an 04' Mini with 9k and the JCW package. I was wondering how much difference adding a CAI would make to this? Also, is there much difference between a JCW CAI and a Dinan?
thanks

 

Adding the CAI will give you an added 1-5 hp. the sound i think is the best part. it is quite addicting and I feel that the throttle response has improved as well. the jcw has a flap that opens and closes to either let sound out or keep it in. the dinan is always open so you'll be able to hear the supercharger whine a bit sooner. I've had my jcw for a day now and I love it. no complaints and all smiles here.

 

I pulled that plug out too. I could see no reason to leave it in.

 

Had mine in for awhile and just recently took the plug out when I upgraded the pulley. You can now hear the whine earlier when you get on it hard. It gives you a less dramatic change of sound at 4500 rpm, but as others have suggested, probably helps breath alittle better at lower RPM. If you like the sound of a supercharger winding up - leave it out!