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Lots of threads on 4" or 5" exhausts on stock engines, and how the stock airbox will flow to 500HP. I have a 5" MBRP and some turbo lag with the stock airbox. Recently I put in an AFE stage II filter and there is much less lag now.
Why so much lag with the stock filter if it allows so much air?
The reason is that is doesn't filter as good as the stock airbox/filter. The AFE has been accused of allowing the turbo to be dusted. You'll have to search the forum for those accusations.
Yeah I have seen the threads. I service mine often and have never ever ever seen any type of dusty residue in the turbo or tubes.
I take my AFE a step further and grease the seal where the scoop fits into (the filtered scoop feeding the compressor side). Maybe I am lucky...who knows
The reason is that is doesn't filter as good as the stock airbox/filter. The AFE has been accused of allowing the turbo to be dusted. You'll have to search the forum for those accusations.
Also K&N filters have been accused of less filtering then a stock filter.
Just be careful if you are still under warranty and you bring you truck in for any turbo related issues. If you turbo needs replacement and its under warranty Ford sends a rep. to inspect and will deny your claim if you have a A/M filter or ram air kit installed.
The Donaldson OEM filter captures more pariculate then a K&N but a K&N will flow better then the Donaldson. If I lived or worked in a dusty construction type of environment, I would ONLY use the Donaldson. However, I have used K&N for years and have never had an issue with dust collecting on the MAF or inlet duct to the throttle body. I live on a 1 mile gravel road and still have no dust issues. Currently, I have a K&N in my X, my ZO6 and my Jetta TDI. If there was a dust issue, it would be very evident in the X, especially with the way th CCV dumps crankcase oil vapor into the turbo. If the K&Ns or other after market filters did not work in benign environments, there would be globs of dust and oil in the intake and on the turbo blades. I have 75,000 miles on my X, 33,000 on my Z and 6,000 on TDI and have no dust accumulation in any vehicle. I just had the turbo out of my X to install studs and the only buildup on my turbo baldes was the black residue produced by the CCV.
You might also do a search on here regarding the 5" exhaust. Some have said that the 5" changes your torque peak and places it higher in the RPM range. I have read posts by others that have used 5" and had more lag on initial throttle tip-in but then had it pick back up as it builds boost higher up on the tach.
You might also do a search on here regarding the 5" exhaust. Some have said that the 5" changes your torque peak and places it higher in the RPM range. I have read posts by others that have used 5" and had more lag on initial throttle tip-in but then had it pick back up as it builds boost higher up on the tach.