Originally Posted by m 135
I know the air-filters are placed at the rear on the 50i,which also makes them hard to change,where as the M versions are toward the front,making it easy to get to if you want after market filters.
I wonder if the different location on the 50i is a negative for air-flow like you mentioned
Could be...I need to look under the hood and see if there's any restriction point. I remember the X5M having two big air boxes right up front.
In the past I had a 987 Boxster S. The air intake was on the side, and it had a restrictor plate that literally had a gap a finger-width wide allowing air in. I removed it and gained an easy 15 hp up top. Not saying there is something similar here, but manufacturers have been known to do this kind of thing.
2015 BMW M4 Alpine white/black
2011 Nissan GTR Red/black - HP Logic tune/midpipe
2013 BMW X5 50i M-sport M-performance Alpine white/black
2011 BMW M3 convertible Jerez black/beige
Gone but not forgotten: '12 X5M, '07 AM SuperVantage, '05 Boxster S, '01 BMW M3,...