[Alext]

I bought some DCI for my 135i + SSTT back in the day. At first I felt it gave a little better throttle response but I couldnt tell if it made more power. Then summer came around and I did a little testing. I spent a lot of time swapping out the stock airbox with the DCI and found an improvement (to my disappointment!) with believe it or not ...the STOCK AIRBOX!

After doing further research I discovered that DCIs could hurt performance. I am glad someone has continued that with the COBB AP.

So I kept the stock airbox for daily driving in traffic. My car felt a lot better plus I have to say I eventually got tired of the vacuum cleaner sound. BMW really did design the stock airbox well. There is A REASON why they spent $$$ designing a cold air feed duct from the front of the car. **I think Mr 5 understands this principle well - hence his new intake design which works**.

I also note the stock airbox has many fins inside - I am guessing to promote laminar flow of air (decrease turbulence) & velocity?

Perhaps if you were pushing 15-16psi the DCI would be of more benefit down the strip....

BTW i am running a DCT Z4 35is these days (and it's noticeably quicker than my 135i!). I have kept the intake stock although I still have my BMS DCI's lying around! IF I decide to push out the numbers with a procede or JB4 then I may consider putting the DCI back in as it is a much easier install in the Z4 engine bay.