I have been looking at doing an S5 UIM swap recently, but the last few posts I read (thread is from 2001) said that the S4 UIM is better on a ported motor.

On my next motor I plan to do a medium to large streetport so I am wondering if anyone has more information then, "I heard the S4 UIM is better for a ported motor"

Thanks

 

I've never heard of this. As far as I've known, the S5 upper intake manifold flows better. I know this is for sure true for the N/A, but I'm not sure about the turbo. Apparently the S4 lower intake manifold flows better than the S5 one though.

 

Sorry I should have specified.
I will be running N/A.

The S4/S4 LIM appear to look different but perform the same, the S5 UIM benefits from the VDI.

 

Anybody have more information?

 

The s5 UIM is better on ALL non-turbo engines. It gives a dyno proven 10-15 HP due to the VDI. The s4 LIM is supposed to be better, though.