A400

I know you guys hate to hear of anything other than the 1.8t, ... but I had a 2.2L-I5T with a really big t57 on it and between the motor sucking and the turbo boosting I broke 2 MAF wires rendering them inoperable, before I found it was a common on 5cyls running the 3" MAF and pulling ~420hp, To go beyond that level a ~4' 928/SQ MAF and a custom harness w/resistors, etc (to go between the alien MAF and stock harness to match the output to what was expected, but thats another story..And I am sure the experts know all about that kind of stuff) The point is that several engineers did a set of calculations of intake velocity for engines pulling ~650 cfm thru the stock and rs2 maf and the velocity was within 100 mph of spped of sound or some rediculous velocity and rips the wires maf from the connections. This is 1 reason that you need a larger housing, another is to reduce the turbulence of the air coming nto the turbo, it is best to eliminate this altogher, which I finally will very soon. A larger MAF has many advantages in certain hi power applications where a lot of air and fuel are burned. All this stuff is somewhere in Audi archives, and it was true at lest in my case. Soon Best of all is to have a filter and a straight shot with the dia necking down immed. b4 the compressor intake, at least in a street app.. I see lots of cars in drag trim running open compressor intakes and wonder how often they rebuild. ramble ramble etc.
Rod

Audi2ptzero

I would have to start with a 6" maf to neck down to my 4" inlet at the turbo.

A400

I have already explained to you what to do with yourself!

YellowA4Turbo Ownz

and increase in volumetric efficency

Audi2ptzero

Only if the maf was smaller then the turbo inlet to start with.

YellowA4Turbo Ownz

Yes, that was my assumption